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.

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.

Suggested role for neutrophil extracellular trap formation in Ewing sarcoma immune microenvironment.

Ewing sarcoma (EWS) is a highly aggressive cancer with a survival rate of 70%-80% for patients with localized disease and under 30% for those with metastatic disease. Tumor-infiltrating neutrophils (TIN) can generate extracellular net-like DNA structures known as neutrophil extracellular traps (NETs). However, little is known about the presence and prognostic significance of tumor-infiltrating NETs in EWS. Herein, we investigated 46 patients diagnosed with EWS and treated in the Tel Aviv Medical Center between 2010 and 2021. TINs and NETs were identified in diagnostic biopsies of EWS by immunofluorescence. In addition, NETs were investigated in neutrophils isolated from peripheral blood samples of EWS patients at diagnosis and following neoadjuvant chemotherapy. The relationships between the presence of TINs and NETs, pathological and clinical features, and outcomes were analyzed. Our results demonstrate that TIN and NETs at diagnosis were higher in EWS patients with metastatic disease compared with those with local disease. High NET formation at diagnosis predicted poor response to neoadjuvant chemotherapy, relapse, and death from disease (p < 0.05). NET formation in peripheral blood samples at diagnosis was significantly elevated among patients with EWS compared with pediatric controls and decreased significantly following neoadjuvant chemotherapy. In conclusion, NET formation seems to have a role in the EWS immune microenvironment. Their presence can refine risk stratification, predict chemotherapy resistance and survival, and serve as a therapeutic target in patients with EWS.

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.

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.

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.

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.

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.

3D-printed Cutting Guides for Lower Limb Deformity Correction in the Young Population.

BACKGROUND: Three-dimensional (3D) virtual surgical planning technology has advanced applications in the correction of deformities of long bones by enabling the production of 3D stereolithographic models, patient-specific instruments and surgical-guiding templates. Herein, we describe the implementation of this technology in young patients who required a corrective osteotomy for a complex 3-plane (oblique plane) lower-limb deformity. PATIENTS AND METHODS: A total of 17 patients (9 males, average age 14.7 y) participated in this retrospective study. As part of preoperative planning, the patients' computerized tomographic images were imported into a post-processing software, and virtual 3D models were created by a segmentation process. Femoral and tibial models and cutting guides with locking points were designed according to the deformity correction plan. They were used for both planning and as intraoperative guides. Clinical parameters, such as blood loss and operative time were compared with a traditional surgical approach group. RESULTS: All osteotomies in the 3D group were executed with the use intraoperative customized cutting guides which matched the preoperative planning simulation and allowed easy fixation with prechosen plates. Surgical time was 101±6.2 minutes for the 3D group and 126.4±16.1 minutes for the control group. The respective intraoperative hemoglobin blood loss was 2.1±0.2 and 2.5+0.3 g/dL.Clinical and radiographic follow-up findings showed highly satisfactory alignment of the treated extremities in all 3D intervention cases, with an average time-to-bone union (excluding 2 neurofibromatosis 1 patients) of 10.3 weeks (range 6 to 20 wk). CONCLUSION: The use of 3D-printed models and patient-specific cutting guides with locking points improves the clinical outcomes of osteotomies in young patients with complex bone deformities of the lower limbs. LEVEL OF EVIDENCE: Level III.

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.

Diverse presentation and tailored treatment of infantile myofibromatosis: A single-center experience.

BACKGROUND: Infantile myofibromatosis (IM) is a rare benign fibrous tumor with diverse clinical presentations and treatments, such as watchful waiting, surgical excision, and low-dose chemotherapy. PROCEDURE: Clinical presentation and tailored treatment of five infants with solitary and generalized IM are described, together with a review of the literature. RESULTS: Three patients underwent total-body magnetic resonance imaging (MRI) at diagnosis and during follow up, which revealed disease extension that aided in designing treatment. Visceral involvement included central nervous system, cardiac, gastrointestinal, muscle, bone, and subcutaneous tissue lesions. The patient with the solitary form of IM was followed up without treatment and had spontaneous improvement. Patients with the multicentric form received intravenous low-dose methotrexate and vinblastine chemotherapy. One patient who received oral methotrexate due to cardiac involvement and unfeasible central line access had excellent results. Recurrence was successfully treated by the same methotrexate and vinblastine regimen as that administered at diagnosis. CONCLUSIONS: We suggest screening all patients with one or more IM lesions by means of total body MRI due to its inherent superior soft tissue resolution. Total-body MRI may also be used for routine follow up. Oral methotrexate can be administered successfully in patients that lack central line access, and recurrent lesions can be treated with the same chemotherapeutic combination as that given at diagnosis. Long-term follow up is needed, since recurrence could appear years after initial presentation of the disease.

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.

Expandable distal femur megaprosthesis: A European Musculoskeletal Oncology Society study on 299 cases.

BACKGROUND AND OBJECTIVES: Expandable distal femur prostheses have become more popular over the last decades, but scientific data is limited. METHODS: A retrospective study was performed, including cases treated between 1986 and 2019 in 15 European referral centers for bone sarcomas. RESULTS: A total of 299 cases were included. Average follow-up was 80 months (range, 8-287 months). Mean patient age was 10 years. Most (80%) of the implants were noninvasive growers and a fixed hinge knee was used more often (64%) than a rotating hinge. Most prosthetic designs showed good (>80%) implant survival at 10 years, but repeat surgery was required for 63% of the patients. The most frequent reason for revision procedure was the completion of lengthening potential. Noninvasive expandable implants showed less risk of infection compared to invasive growers (11.8% vs 22.9% at 10 years). No difference in aseptic loosening was found between cemented and uncemented stems. CONCLUSIONS: This study shows the increasing popularity of expandable distal femur prostheses, with overall good results for function and implant survival. However, repeat surgery is frequently required, especially in patients under the age of 10 years old. Infection is less frequent in noninvasive growers compared to implants that require invasive lengthening procedures.

3D imaging and stealth navigation instead of CT guidance for radiofrequency ablation of osteoid osteomas: a series of 52 patients.

BACKGROUND: Osteoid osteomas are benign bone neoplasms that may cause severe pain and limit function. They are commonly treated by radiofrequency ablation (RFA) through a needle inserted into the nidus of the lesion under CT guidance, which is associated with exposure of young patients to relatively high dose of radiation. The objective of this study was to investigate the amount of radiation, effectiveness and safety of an alternative imaging approach, the 3D image-guided (O-arm) technology and the Stealth navigation. METHODS: We retrospectively reviewed 52 electronic medical files of patients (mean age 24.7 years, range 8-59 years) who were treated with thermal ablation of benign osteoid osteomas guided by the navigated O-arm-assisted technique in our institution between 2015 and 2017. Data were extracted on the associated complications, the reduction in pain at 3 months and one year postoperatively, and the amount of radiation administered during the procedure. RESULTS: The level of pain on a visual analogue scale decreased from the preoperative average of 7.73 to 0 at the 3-month follow-up. The mean dose-length product was 544.7 mGycm2 compared to the reported radiation exposure of 1971-7946 mGycm2 of CT-guided radio ablations. The one intra-operative complication was a superficial burn in the subcutaneous lesion in a tibia that was treated locally with no major influence on recovery. CONCLUSIONS: RFA ablation guided by 3D O-arm stealth navigation is as effective as the traditional CT-guided technique with the advantage of lower radiation exposure. TRIAL REGISTRATION: Retrospective study number 0388-17-TLV at Tel Aviv Sourasky Medical Center IRB, approved at 25.10.17.

Pathological fracture risk assessment in patients with femoral metastases using CT-based finite element methods. A retrospective clinical study.

Physician recommendation for prophylactic surgical fixation of a femur with metastatic bone disease (MBD) is usually based on Mirels' criteria and clinical experience, both of which suffer from poor specificity. This may result in a significant number of these health compromised patients undergoing unnecessary surgery. CT-based finite element analyses (CTFEA) have been shown to accurately predict strength in femurs with metastatic tumors in an ex-vivo study. In order to assess the utility of CTFEA as a clinical tool to determine the need for fixation of patients with MBD of the femur, an ad hoc CTFEA was performed on a retrospective cohort of fifty patients. Patients with CT scans appropriate for CTFEA analysis were analyzed. Group 1 was composed of 5 MBD patients who presented with a pathologic femoral fracture and had a scan of their femurs just prior to fracture. Group 2 was composed of 45 MBD patients who were scheduled for a prophylactic surgery because of an impending femoral fracture. CTFEA models were constructed for both femurs for all patients, loaded with a hip contact force representing stance position loading accounting for the patient's weight and femur anatomy. CTFEA analysis of Group 1 patients revealed that they all had higher tumor associated strains compared to typical non-diseased femur bone strains at the same region (>45%). Based on analysis of the 5 patients in Group 1, the ratio between the absolute maximum principal strain in the vicinity of the tumor and the typical median strain in the region of the tumor of healthy bones (typical strain fold ratio) was found to be the 1.48. This was considered to be the predictive threshold for a pathological femoral fracture. Based on this typical strain fold ratio, twenty patients (44.4%) in Group 2 were at low risk of fracture and twenty-five patients (55.5%) high risk of fracture. Eleven patients in Group 2 choose not to have surgery and none fractured in the 5month follow-up period. CTFEA predicted that seven of these patients were below the pathological fracture threshold and four above, for a specificity of 63% Based on CTFEA, 39% of the patients with femoral MBD who were referred and underwent prophylactic stabilization may not have needed surgery. These results indicate that a prospective randomized clinical trial evaluating CTFEA as a criterion for determining the need for surgical stabilization in patients with MBD of the femur may be warranted.

Hip arthroscopy for intra-capsular benign tumors: a case series.

The purpose of this study is to demonstrate the assessment of intra-capsular femoral head and neck tumors, and to describe the arthroscopic surgical technique used to resect and fill the bone defects. Three cases of benign femoral head and neck lesions are presented. Two benign enchondromas and one benign osteochondroma were resected arthroscopically. Traction was used in one case. Modified Harris Hip Score improved in all three cases to scores of 95 or greater with an average improvement of 16 points with a minimum follow up of 15 months. Arthroscopic surgical resection of intra-capsular femoral hip lesions offers an effective alternative to open resection. This technique offered good outcomes in the limited cohort. We suggest that arthroscopic resection of intra-capsular femoral hip lesions be considered in relevant cases as an alternative to open resection.