Imaging-Based Deep Learning for Predicting Desmoid Tumor Progression.

Desmoid tumors (DTs) are non-metastasizing and locally aggressive soft-tissue mesenchymal neoplasms. Those that become enlarged often become locally invasive and cause significant morbidity. DTs have a varied pattern of clinical presentation, with up to 50-60% not growing after diagnosis and 20-30% shrinking or even disappearing after initial progression. Enlarging tumors are considered unstable and progressive. The management of symptomatic and enlarging DTs is challenging, and primarily consists of chemotherapy. Despite wide surgical resection, DTs carry a rate of local recurrence as high as 50%. There is a consensus that contrast-enhanced magnetic resonance imaging (MRI) or, alternatively, computerized tomography (CT) is the preferred modality for monitoring DTs. Each uses Response Evaluation Criteria in Solid Tumors version 1.1 (RECIST 1.1), which measures the largest diameter on axial, sagittal, or coronal series. This approach, however, reportedly lacks accuracy in detecting response to therapy and fails to detect tumor progression, thus calling for more sophisticated methods. The objective of this study was to detect unique features identified by deep learning that correlate with the future clinical course of the disease. Between 2006 and 2019, 51 patients (mean age 41.22 ± 15.5 years) who had a tissue diagnosis of DT were included in this retrospective single-center study. Each had undergone at least three MRI examinations (including a pretreatment baseline study), and each was followed by orthopedic oncology specialists for a median of 38.83 months (IQR 44.38). Tumor segmentations were performed on a T2 fat-suppressed treatment-naive MRI sequence, after which the segmented lesion was extracted to a three-dimensional file together with its DICOM file and run through deep learning software. The results of the algorithm were then compared to clinical data collected from the patients' medical files. There were 28 males (13 stable) and 23 females (15 stable) whose ages ranged from 19.07 to 83.33 years. The model was able to independently predict clinical progression as measured from the baseline MRI with an overall accuracy of 93% (93 ± 0.04) and ROC of 0.89 ± 0.08. Artificial intelligence may contribute to risk stratification and clinical decision-making in patients with DT by predicting which patients are likely to progress.

Automatic segmentation of femoral tumors by nnU-net.

BACKGROUND: Metastatic femoral tumors may lead to pathological fractures during daily activities. A CT-based finite element analysis of a patient's femurs was shown to assist orthopedic surgeons in making informed decisions about the risk of fracture and the need for a prophylactic fixation. Improving the accuracy of such analyses ruqires an automatic and accurate segmentation of the tumors and their automatic inclusion in the finite element model. We present herein a deep learning algorithm (nnU-Net) to automatically segment lytic tumors within the femur. METHOD: A dataset consisting of fifty CT scans of patients with manually annotated femoral tumors was created. Forty of them, chosen randomly, were used for training the nnU-Net, while the remaining ten CT scans were used for testing. The deep learning model's performance was compared to two experienced radiologists. FINDINGS: The proposed algorithm outperformed the current state-of-the-art solutions, achieving dice similarity scores of 0.67 and 0.68 on the test data when compared to two experienced radiologists, while the dice similarity score for inter-individual variability between the radiologists was 0.73. INTERPRETATION: The automatic algorithm may segment lytic femoral tumors in CT scans as accurately as experienced radiologists with similar dice similarity scores. The influence of the realistic tumors inclusion in an autonomous finite element algorithm is presented in (Rachmil et al., "The Influence of Femoral Lytic Tumors Segmentation on Autonomous Finite Element Analyses", Clinical Biomechanics, 112, paper 106192, (2024)).

Mechanical failure of distal femur mega prosthesis due to polyaryl-ether-ether-ketone (PEEK) hinge component.

BACKGROUND: Polyaryl-ether-ether-ketone (PEEK) has gained popularity as a substrate for orthopaedic hardware due to its desirable properties such as heat and deformation resistance, low weight, and ease of manufacturing. However, we observed a relatively high failure rate of PEEK-based hinges in a distal femur reconstruction system. In this study, we aimed to evaluate the proportion of patients who experienced implant failure, analyse the mechanism of failure, and document the associated clinical findings. METHODS: We conducted a retrospective cohort study, reviewing the medical charts of 56 patients who underwent distal femur resection and reconstruction with a PEEK Optima hinge-based prosthesis between 2004 and 2018. Concurrently, we performed a clinical and biomechanical failure analysis. RESULTS: PEEK component failure occurred in 21 out of 56 patients (37.5%), with a mean time to failure of 63.2 months (range: 13-144 months, SD: 37.9). The survival distributions of PEEK hinges for males and females were significantly different (chi-square test, p-value = 0.005). Patient weight was also significantly associated with the hazard of failure (Wald's test statistic, p-value = 0.031). DISCUSSION: Our findings suggest that PEEK hinge failure in a distal femur reconstruction system is correlated with patient weight and male gender. Retrieval analysis revealed that failure was related to fretting and microscopic fractures due to cyclic loading, leading to instability and mechanical failure of the PEEK component in full extension. Further assessment of PEEK-based weight bearing articulating components against metal is warranted.

The influence of femoral lytic tumors segmentation on autonomous finite element analysis.

BACKGROUND: The validated CT-based autonomous finite element system Simfini (Yosibash et al., 2020) is used in clinical practice to assist orthopedic oncologists in determining the risk of pathological femoral fractures due to metastatic tumors. The finite element models are created automatically from CT-scans, assigning to lytic tumors a relatively low stiffness as if these were a low-density bone tissue because the tumors could not be automatically identified. METHODS: The newly developed automatic deep learning algorithm which segments lytic tumors in femurs, presented in (Rachmil et al., 2023), was integrated into Simfini. Finite element models of twenty femurs from ten CT-scans of patients with femoral lytic tumors were analyzed three times using: the original methodology without tumor segmentation, manual segmentation of the lytic tumors, and the new automatic segmentation deep learning algorithm to identify lytic tumors. The influence of explicitly incorporating tumors in the autonomous finite element analysis on computed principal strains is quantified. These serve as an indicator of femoral fracture and are therefore of clinical significance. FINDINGS: Autonomous finite element models with segmented lytic tumors had generally larger strains in regions affected by the tumor. The deep learning and manual segmentation of tumors resulted in similar average principal strains in 19 regions out of the 23 regions within 15 femurs with lytic tumors. A high dice similarity score of the automatic deep learning tumor segmentation did not necessarily correspond to minor differences compared to manual segmentation. INTERPRETATION: Automatic tumor segmentation by deep learning allows their incorporation into an autonomous finite element system, resulting generally in elevated averaged principal strains that may better predict pathological femoral fractures.

Does cryotherapy decrease the local recurrence rate in the treatment of an aneurysmal bone cyst? A comparative assessment.

Curettage with or without the use of adjuvants is the standard of care in the treatment of an aneurysmal bone cyst (ABC). Historically, our approach combined curettage, high-speed burr drilling, and cryoablation. However, treatments varied based on age, tumor location, and surgeon preference. We asked: (1) Does cryoablation in addition to curettage and burr drilling decrease the local recurrence rates? (2) Are there any risk factors for the local recurrence rate? (3) Does cryoablation improve postsurgical functional outcomes in these patients? Patients treated for an ABC, between January 2006 and December 2019 were included in this retrospective analysis. Patient and surgical characteristics, such as age, gender, tumor location, type of treatment, time of follow-up, recurrence rate, and functional outcome measured by the Musculoskeletal Tumor Society Score 1993 (MSTS93) score were compared between those treated with and without cryoablation. Both groups, without cryoablation (n = 88) and with cryoablation (n = 42), showed no significant difference in local recurrence rates (9.1% vs. 7.1%, p = 0.553) and functional outcomes as measured by the MSTS93 score (28.9 vs. 27.8, p = 0.262). Risk factors analyzed did not significantly affect local recurrence risk, except for secondary ABC diagnosis (p = 0.017). The cryoablation group had a more extended follow-up (45.6 vs. 73.2 months, p < 0.001), reflecting a shift in practice over time. We found no significant difference in local recurrence rate or functional outcome in patients treated with or without cryoablation. Formal curettage with additional high-speed burr drilling provides effective tumor control and favorable functional outcomes, negating the need for adjuvant cryoablation.

Intraoperative three-dimensional navigation for surgical treatment of osteoid osteoma in the upper extremity: A series of 19 cases.

The surgical treatment for osteoid osteoma (OO) in the upper extremity is challenging due to the difficulty in locating the lesion and the crowding of sensitive structures within the anatomy. This study aimed to describe the outcomes of navigated minimally invasive radiofrequency ablation and those of navigated mini open-intralesional curettage in treating these lesions. Nineteen consecutive patients with OO in the upper limb who underwent navigated surgery were included. The average QuickDASH and Numeric Pain Rating Scale improved from 62.2 ± 23.7 to 11.7 ± 16.9 and from 8.1 ± 1.6 to 0.5 ± 1.8, respectively (p < .01 each) following the procedure. Two complications were recorded: one patient had persistent radial nerve palsy, and one patient had transient partial radial nerve weakness. In conclusion, navigation is an important tool in the surgical treatment of OO in the upper limb. A mini open approach to identify and protect neurovascular structures is recommended.

Favorable outcomes of navigated percutaneous ablation and cementoplasty of bone metastasis in the extremities and pelvis-a case series of 13 cases.

OBJECTIVES: Palliative treatment options for bone metastasis are limited, especially in cases where standard protocols have already failed. The purpose of this study was to evaluate the efficacy and safety of percutaneous ablation, either by cryoablation or radiofrequency, combined with percutaneous cementoplasty using cone-beam guided navigation. The objective was to relieve symptoms and improve functionality in patients suffering from pain secondary to bone metastases, as well as evaluate local disease progression post ablation. METHODS: We conducted a retrospective study of 13 patients (average age 63.6 ± 9.8, nine females) with symptomatic skeletal metastases treated using 3D imaging with navigation and followed for at least 12 months. The treatment protocol was implemented either after failure of first line treatment, or as first line when mechanical instability was present. Percutaneous lesion ablation was performed along with percutaneous cementation. RESULTS: In this study, we observed a statistically significant decrease in pain. The mean Visual Analog Scale pain score decreased from 7.1 ± 0.4 prior to CRA/RFA to 2.2 ± 0.3 after the procedure (p < 0.001). At the 12-months follow-up, all patients were able to ambulate with no assistance (Eastern Cooperative Oncology Group <2). One minor adverse event (paresthesia) and one major adverse event (drop foot) were resolved at 1 year of follow-up. CONCLUSIONS: Treatment of bone metastasis with RFA and CRA in conjunction with cementoplasty using Cone-beam computed tomography navigation provides patients with significant palliative outcomes and in most cases, local tumor control.

5-ALA photodynamic ablation of fibroblastic soft-tissue tumors.

BACKGROUND: Fibroblastic soft-tissue tumors share enzymatic anomalies that result in excessive intracellular conversion of 5-aminolevulinic acid (5-ALA) to protoporphyrin IX, a photosensitizer which induces cellular apoptosis upon exposure to visible red light at a wavelength of 635 nm. We hypothesized that red light illumination of the surgical bed remaining after resection of fibroblastic tumors will result in destruction of microscopic tumor residua and may decrease the likelihood of local tumor recurrence. METHODS: Twenty-four patients with desmoid tumors, solitary fibrous tumors (SFT), and dermatofibrosarcoma protuberans (DFSP) received oral 5-ALA prior to resection of their tumors. Following tumor resection, the exposed surgical bed was illuminated with red light at a wave length of 635 nm at a dose of 150 J/cm2 for 33 min. RESULTS: Treatment with 5-ALA was associated with minor side effects that included nausea and transient elevation of transaminases. Local tumor recurrence was detected in 1 of the 10 patients with desmoid tumors who had not undergone any previous surgery, none in the 6 patients who had SFT and 1 of the 5 patients who had DFSP. CONCLUSIONS: 5-ALA photodynamic therapy of fibroblastic soft-tissue tumors may result in decreased likelihood of local tumor recurrence. It is associated with minimal side effects and should be considered as adjuvant to tumor resection in these cases.

On the influence of computed tomography's slice thickness on computer tomography based finite element analyses results.

BACKGROUND: Patient-specific autonomous finite element analyses of femurs, based on clinical computed tomography scans may be used to monitor the progression of bone-related diseases. Some CT scan protocols provide lower resolution (slice thickness of 3 mm) that affects the accuracy. To investigate the impact of low-resolution scans on the CT-based finite element analyses results, identical CT raw data were reconstructed twice to generate a 1 mm ("gold standard") and a 3 mm slice thickness scans. METHODS: CT-based finite element analyses of twenty-four femurs (twelve patients) under stance and sideways fall loads were performed based on 1 and 3 mm slice thickness scans. Bone volume, load direction, and strains were extracted at different locations along the femurs and differences were evaluated. FINDINGS: Average differences in bone volume were 1.0 ± 1.5%. The largest average difference in strains in stance position was in the neck region (11.0 ± 13.4%), whereas in other regions these were much smaller. For sidewise fall loading, the average differences were at most 9.2 ± 16.0%. INTERPRETATION: Whole-body low dose CT scans (3 mm-slice thickness) are suboptimal for monitoring strain changes in patient's femurs but may allow longitudinal studies if larger than 5% in all areas and larger than 12% in the upper neck. CT-based finite element analyses with slice thickness of 3 mm may be used in clinical practice for patients with smoldering myeloma to associate changes in strains with progression to active myeloma if above ∼10%.

Less is better than more with resection of periacetabular tumors - A retrospective 16 years study and literature review.

Introduction: Wide resections of periacetabular tumors create a sizeable bony defect that inevitably results in severe loss of function. Reconstruction of such defects usually requires using large metal implants, a feature associated with considerable surgery extension and complications. The aim of this study is to report resection with no reconstruction of the bony defect. In this retrospective study, we reviewed a consecutive series of 16 patients diagnosed with malignant periacetabular tumors and underwent en-bloc resection without reconstructing their remaining bone defect. Methods: Records were reviewed of 16 consecutive patients diagnosed with malignant periacetabular tumors and underwent en-bloc resection without reconstructing their remaining bony defect. Measurements included: the duration of surgery, blood loss, hemoglobin levels and the need for blood transfusions, data on other hospitalization characteristics, and intraoperative and postoperative complications. Results: Sixteen patients with malignant periacetabular bone tumors and extensive bone destruction underwent wide periacetabular tumor resection with a mean follow-up of 75 months and a mean age of 53 years. The average HOOS score was 46 (range: 20 to 76), and the mean MSTS score was 13% (range: 0 to 15). The mean operative time was 4.1 h, and the mean blood loss was 1200 ml. At their most recent follow-up, patients had a mean shortening of their operated extremity of 4.8 cm, and all could ambulate with assisting devices. Conclusion: Wide resection of periacetabular tumors without reconstruction provides acceptable levels of function and was associated with shorter surgical time, less blood loss and fewer postoperative complications compared to resection with reconstruction. Therefore, this approach may be considered a viable surgical option in patients with an extensive malignant periacetabular. Level III: Retrospective study.

Radiation Therapy Before Repeat Wide Resection for Unplanned Surgery of Soft Tissue Sarcoma ("Oops" Operation) Results in Improved Disease-Free Survival.

Purpose: The main goal of treatment of soft-tissue sarcomas is achieving wide negative margins to improve local control and prevent recurrence. The role of radiation therapy (RT) is well established in sarcomas of the extremities; however, its role in unplanned surgery of soft-tissue sarcoma (when a mass presumed to be benign is resected and the pathology comes back as sarcoma, usually referred to as an "oops" operation) is inconclusive. This article reports on the effect of RT after an unplanned surgery before the reresection. Methods and Materials: A total of 65 patients who had undergone an unplanned resection of a postoperatively diagnosed soft-tissue sarcoma were treated with RT and/or surgery and retrospectively evaluated for disease progression. Treatment started with RT in 49 cases (75.4%), including 8 cases of no further surgery. A repeat wide resection was performed directly after the initial surgery in 16 patients, followed by RT in 15 of them. Results: The disease recurred in 7 out of 49 patients (14.3%) who received RT first and in 9 out of 16 (56.25%) who underwent reoperation before RT (P = .001). Disease-free progression was higher in cases of low-grade malignancy (P = .049). A clinical diagnosis of lipoma was associated with a better outcome than a diagnosis of nonlipoma (P = .034). The presence of residual tumor at reoperation did not affect disease control. Patient age, time between symptom onset and diagnosis, hospital level of initial diagnosis (tertiary versus nontertiary), anatomic site, tumor size, and margin status at the initial excisional biopsy were not significantly correlated with the outcome. Conclusion: Initiating treatment with RT followed by unplanned "oops" resection of soft-tissue sarcoma before the reresection improved disease-free survival as opposed to vice versa.

Internal Hemipelvectomy for primary bone sarcomas using intraoperative patient specific instruments- the next step in limb salvage concept.

BACKGROUND: During pelvic Sarcoma resections, Surgeons often struggle to obtain negative margins while minimizing collateral damage and maintaining limb function. These complications are usually due to the complex anatomy of the pelvis. Here we present an accurate 3D surgical approach, including pre-operative printing of models and intraoperative patient-specific instruments (PSIs) for optimizing pelvic sarcoma resections. METHODS: This single-center retrospective study (N = 11) presents surgical, functional, and oncological outcomes of patients (average age 14.6 +/- 7.6 years, 4 males) who underwent pelvic sarcoma resections using a 3D surgical approach between 2016 and 2021. All patients were followed up for at least 24 months (mean = 38.9 +/- 30.1 months). RESULTS: Our results show promising surgical, oncological, and functional outcomes. Using a 3D approach, 90.9% had negative margins, and 63.6% did not require reconstruction surgery. The average estimated blood loss was 895.45 ± 540.12 cc, and the average surgery time was 3:38 ± 0.05 hours. Our results revealed no long-term complications. Three patients suffered from short-term complications of superficial wound infections. At 24 month follow up 72.7% of patients displayed no evidence of disease. The average Musculoskeletal Tumor Society (MSTS) score at 12 months was 22.81. CONCLUSION: 3D technology enables improved accuracy in tumor resections, allowing for less invasive procedures and tailored reconstruction surgeries, potentially leading to better outcomes in function and morbidity. We believe that this approach will enhance treatments and ease prognosis for patients diagnosed with pelvic sarcoma and will become the standard of care in the future.

Three dimensional printing as an aid for pre-operative planning in complex cases of total joint arthroplasty: A case series.

Purpose: Digital templating is an essential aspect of pre-operative planning for total joint arthroplasty procedures. For complex cases of joint reconstruction, the standard templating software is insufficient to achieve the desired accuracy. 3D printing significantly aids the pre-operative planning in complicated cases of joint reconstruction and offers immense potential towards improving outcomes in these cases. The purpose of the present study is to present the various ways in which 3D printing has aided our department in facilitating complex cases of lower extremity reconstruction. Methods: Data was retrospectively retrieved for all patients that underwent total hip arthroplasty (THA) and total knee arthroplasty (TKA) with the aid of 3D printing technology at our institution between January 2016-February 2021. Patient pain was determined before and after surgery using the visual analogue scale (VAS). Patient reported outcome measures (PROMs) were additionally analyzed using the hip disability and osteoarthritis outcome score (HOOS) and knee injury and osteoarthritis outcome score (KOOS). Results: The final study population consisted of 39 patients that underwent TKA or THA procedures with the use of 3D printing. Twenty-four (61.5%) of the surgeries in the study were THA procedures, whereas 15 (38.5%) were TKA procedures. The average VAS for patients reduced from 8.4% before surgery to 5.4% after surgery (p < 0.001). The mean KOOS of patients that underwent TKA was 17.33 ± 9.33 (43%) and the mean HOOS of patients that underwent THA was 13.79 ± 6.6 (42%). Conclusions: The following series demonstrates the ability by which 3D printing facilitates complex cases of hip and knee reconstruction. 3D printing offers an improvement in understanding of patient specific anatomy, enhancing patient outcomes. Departments should consider the use of 3D printing technology as an adjunct when performing complex cases of lower extremity reconstruction.

Intraoperative three-dimensional navigation for surgical treatment of osteoid osteoma in the foot and ankle - A series of 14 cases.

BACKGROUND: The surgical treatment for osteoid osteoma (OO) in the foot and ankle is challenging. It is difficult to locate the lesion and the anatomy is crowded by sensitive structures. The purpose of this study was to describe the outcomes of navigated mini open-intralesional curettage (NMIC) or navigated minimally invasive radiofrequency ablation (NMRFA) in treating these lesions. METHODS: All patients who underwent surgery for OO in the foot and ankle between 2015 and 2020 were included. O-arm navigation was used in All procedures. The choice of NMIC versus NMRFA was made by the surgeon according to the location of the lesion and its proximity to sensitive anatomic structures. RESULTS: Fourteen patients were included. Ten were operated by NMRFA and 4 by NMIC. All patients' symptoms related to OO resolved following a single procedure. Average AOFAS score increased by 18.7 (P < .001). Three patients had the following complications: pathologic fracture, superficial infection and transient deep peroneal nerve sensory loss. CONCLUSION: Navigated surgical treatment of OO in the foot and ankle is accurate, efficient and safe.

Intercalary and geographic lower limb tumor resections with the use of 3D printed Patient Specific Instruments- when less is more.

Background: Primary bone sarcomas are associated with critically sized bone defects and require complete resection with negative margins. Recent advancements in health care have pioneered novel approaches such as the implementation of 3D surgical technologies. This study presents oncological and functional outcomes following tumor resections of long bones with the use of customized 3D-printed Patient Specific Instruments (PSIs). Methods: This single-center retrospective study is comprised of seventeen patients who underwent either intercalary (N = 12) or geographic (N = 5) resections with various reconstruction methods including allograft (N = 8), vascularized fibula (Capanna) (N = 7), and 3D printed customized titanium implants (N = 2), between the years 2016-2020. All patients were operated on with a 3D surgical workflow, including intraoperative PSIs, and were followed up postoperatively for at least 12 months (average 31.40 ± 12.13 months) to assess oncological and functional outcomes. Results: All patients demonstrated negative surgical margins, apart from one patient who had planned positive margins. Three patients suffered from short-term complications, and three patients underwent revision surgery due to graft non-union or pathological fracture. One patient suffered from local recurrence and underwent above-knee amputation. Three patients suffered from lung metastasis. MSTS at 12-month follow-up was 26.9.±5.87. Conclusion: Customized 3D-printed osteotomy PSIs provide surgeons with a novel tool for optimizing bone resection and reconstruction in long bones surgeries, thus minimizing overall tissue trauma and reducing the risk of damage to nervous and vascular structures. This study demonstrates that the use of PSIs has the potential to improve functional and oncological outcomes. We believe that this technique will become increasingly popular in the future as a widely applicable, highly accurate, cost-effective optimization tool.

Assessing hip fracture risk in type-2 diabetic patients using CT-based autonomous finite element methods : a feasibility study.

AIMS: Type 2 diabetes mellitus (T2DM) impairs bone strength and is a significant risk factor for hip fracture, yet currently there is no reliable tool to assess this risk. Most risk stratification methods rely on bone mineral density, which is not impaired by diabetes, rendering current tests ineffective. CT-based finite element analysis (CTFEA) calculates the mechanical response of bone to load and uses the yield strain, which is reduced in T2DM patients, to measure bone strength. The purpose of this feasibility study was to examine whether CTFEA could be used to assess the hip fracture risk for T2DM patients. METHODS: A retrospective cohort study was undertaken using autonomous CTFEA performed on existing abdominal or pelvic CT data comparing two groups of T2DM patients: a study group of 27 patients who had sustained a hip fracture within the year following the CT scan and a control group of 24 patients who did not have a hip fracture within one year. The main outcome of the CTFEA is a novel measure of hip bone strength termed the Hip Strength Score (HSS). RESULTS: The HSS was significantly lower in the study group (1.76 (SD 0.46)) than in the control group (2.31 (SD 0.74); p = 0.002). A multivariate model showed the odds of having a hip fracture were 17 times greater in patients who had an HSS ≤ 2.2. The CTFEA has a sensitivity of 89%, a specificity of 76%, and an area under the curve of 0.90. CONCLUSION: This preliminary study demonstrates the feasibility of using a CTFEA-based bone strength parameter to assess hip fracture risk in a population of T2DM patients. Cite this article: Bone Joint J 2021;103-B(9):1497-1504.

Cryo-surgery for symptomatic extra-abdominal desmoids. A proof of concept study.

BACKGROUND AND OBJECTIVE: Extra abdominal desmoid tumors are rare, highly aggressive, and invasive benign soft tissue tumors. Current treatment modalities show high levels of recurrence and comorbidities. Cryo-surgery as an alternative was subsequently investigated. METHODS: In this retrospective, single center study 11 patients showing symptomatic tumors were treated with individualized cryo-surgery. Treatment protocol included preoperative planning using computer rendered 3D models, intraoperative navigation and execution using cone beam guidance, and postoperative magnetic resonance imaging image analysis using a gaussian mixture model software. Subjective outcomes were reported using Short Form Health Survey (SF-36) questionnaires. RESULTS: Sixteen ablations were performed, each demonstrating a complete match with the determined preoperative plan and model. A total of 9/11 (82%) of patients showed improvements in symptoms and a reduction in tumor volume while 2/11 (18%) did not. Average reduction in tumor volume and viable segments were 36.7% (p = 0.0397) and 63.3% (p = 0.0477), respectively. Mild complications according to the SIR Adverse Event Classification Guidelines were experienced in 3/16 (19%) ablations. SF-36 scores showed a statistically significant improvement (p = 0.0194) in the mental health category and a nonsignificant (p = 0.8071) improvement in the physical health category. CONCLUSION: Cryo-surgery using the three-phase protocol as described may improve the overall outcome of future ablation procedures.

Computer-assisted surgical planning of complex bone tumor resections improves negative margin outcomes in a sawbones model.

PURPOSE: Several technologies have been implemented in orthopedic surgery to improve surgical outcomes, usually focusing on more accurate execution of a surgical plan, but the development of the plan itself is also of great importance. The purpose of this study is to examine whether the use of preoperative computer planning platforms can improve the surgical plan? METHODS: Eight surgeons created a preoperative surgical plan to resect a distal femur parosteal osteosarcoma in two settings: (1) Using a 2-D and 3-D CT scan only (current standard); and (2) using a computer-assisted planning platform. The plans were thereafter virtually executed using a novel surgical navigation system and a Sawbones model. This simulated model was derived from, and identical to, an actual patient scenario. The outcomes of interest were the number of positive margin cuts, and the volume of the resected specimen. RESULTS: Using the surgical plan developed with computer assistance, there were 4 positive margin cuts made by 2 surgeons. In comparison, using standard planning, there were 14 positive margin cuts made by all 8 surgeons (p = 0.02). The resection volume was larger in the computer-assisted plans (96 ± 10 mm3) than in the standard plans (88 ± 7 mm3) (p = 0.055). CONCLUSIONS: Computer-assisted planning significantly decreased the risk of a positive margin resection in this Sawbones tumor model used to simulate resection of a primary bone sarcoma. This proof of concept study highlights the importance of advanced surgical planning and sets the ground for developing beneficial surgical planning systems.

Patient-specific computed tomography-based finite element analysis: a new tool to assess fracture risk in benign bone lesions of the femur.

BACKGROUND: Most benign active and latent lesions of proximal femur do not predispose a patient to a pathologic fracture. Nonetheless, there is a tendency to perform internal fixation due to the lack of accurate clinical tools that may reliably confirm low risk of pathologic fracture. As many as 30% of these surgeries may be unnecessary. A patient-specific CT-based finite element analysis may quantify bone strength and risk of fracture under normal weight-bearing conditions. METHODS: The clinical relevance of such finite element analysis was investigated in a retrospective study on a cohort of 17 patients. Finite element analysis results (high risk = indication for surgery, low or moderate risk = follow-up) were compared to actual clinical decisions (surgery vs follow-up). All patients predicted by the finite element analysis as high risk underwent internal fixation and had good outcomes (n = 6). FINDINGS: Four of the 11 low- and moderate-risk finite element analysis patients (36%) were operated immediately, and seven (64%) were either operated after a delay of at least 6 months or were never operated. None sustained a pathologic fracture. Patients who were predicted as low fracture risk by finite element analysis remained fracture-free for a minimal period of 6 months. Prediction of high risk of pathologic fracture by finite element analysis was in complete agreement with the conventional clinical evaluation. INTERPRETATION: We consider finite element analysis a promising decision support system for the management of patients with benign tumors of femur, and that it may reliably endorse the decision to withhold surgery for patients at low fracture-risk.

Tranexamic acid in hip hemiarthroplasty.

BACKGROUND: Intraoperative use of tranexamic acid (TXA) has been proven to reduce the administration of allogenic blood transfusion in total joint arthroplasty (TJA) patients. Data on TXA efficacy in reducing blood loss in trauma patients undergoing hip hemiarthroplasty are sparse, and its use is not yet well-established. The purpose of this study was to assess the efficacy and safety of intraoperative TXA use in patients undergoing hip hemiarthroplasty as treatment for intracapsular femoral neck fracture. METHODS: This is a historical cohort of patients who underwent hip hemiarthroplasty in a tertiary medical center between 2011 and 2019, with minimum follow-up of one year. The cohort was divided into one group of patients who received intraoperative TXA treatment and another group that did not. Blood loss, peri­ and postoperative complications, readmissions, and short- and long-term mortality were compared between groups. RESULTS: Of the 1722 consecutive patients (601 males and 1121 females) who underwent hip hemiarthroplasty who were included in this study, 504 were in the "TXA" group and 1218 were in the "non-TXA" group. TXA use significantly reduced 30-day mortality (4.6% vs 7.3%, respectively, p < 0.046) and perioperative blood loss, as indicated by changes in hemoglobin levels before and after surgery (Δ-1.38 gr/dL vs Δ-1.76 gr/dL, p < 0.001), and by administration of allogenic blood transfusions (17.5% vs 44.4%, p < 0.001). CONCLUSIONS: Similar to the known effect of TXA in TJA patients, the use of TXA treatment in patients undergoing hip hemiarthroplasty led to a significant reduction in 30-day mortality, in postoperative blood loss and in the proportion of patients requiring allogenic blood transfusions.