Proximal femoral tumor resection followed by joint prosthesis replacement: a systematic review and meta-analysis.

BACKGROUND: This study aimed to determine the prognostic outcome of hip joint replacement after resection of proximal femoral tumors by reviewing original studies. METHODS: Two researchers independently searched PubMed, Embase, Cochrane Library, and Web of Science databases from inception to July 17, 2022. Then, the literature was screened by inclusion criteria. The basic information, primary outcomes, and secondary outcomes were extracted for weighted combined analysis. The quality of the included literature was evaluated using the Newcastle-Ottawa scale. RESULTS: Twenty-four retrospective cohort studies comprising 2081 patients were included. The limb salvage rate was 98%. The survival rates at 1, 2, 3, 4, and 5 years were 80, 72, 65, 64, and 55% for patients with primary tumors and the rate at 1, 2, 3, 4, and 5 years were 44, 25, 17, 14, and 11% for patients with bone metastases, respectively. CONCLUSION: As chemotherapy and radiotherapy treatment progressed, joint reconstruction after proximal femoral tumor resection improved patients' function and quality of life.

What Factors Are Associated With Stem Breakage in Distal Femoral Endoprosthetic Replacements Undertaken for Primary Bone Tumors?

BACKGROUND: The advantages of distal femoral replacement prostheses for reconstructions after tumors are well known; one such implant, the Global Modular Replacement System (GMRS), has been widely used since 2003. Although implant breakage has been reported, the frequency of this event has varied across different studies. QUESTIONS/PURPOSES: (1) What percentage of patients who underwent distal femur resection and replacement using the GMRS for primary bone tumors at one center experienced stem breakage? (2) At what timepoints did these breakages occur, and what factors were common among the stems that broke? METHODS: We performed a retrospective study of all patients who underwent distal femur resection and replacement using the GMRS for a diagnosis of primary bone sarcoma by the Queensland Bone and Soft-tissue Tumor service from 2003 to 2020 who had a minimum of 2 years of follow-up. Standard follow-up for primary bone sarcoma involves radiographic imaging of the femur at 6 weeks and 3 months postoperatively and yearly thereafter. From a chart review, we identified patients with femoral stem breakage. Patient and implant details were recorded and analyzed. A total of 116 patients had undergone a distal femoral replacement with the GMRS prosthesis for primary bone sarcoma; however, 6.9% (eight of 116 patients) died before completing the 2-year follow-up period and were excluded. Of the remaining 108 patients, 15% (16 patients) had died at the time of this review; however, given that they completed the 2-year follow-up period and did not experience stem breakage, they were included. Furthermore, 15% (16 patients) were considered lost to follow-up and excluded because they have not been seen in the past 5 years but were not known to have died or experienced stem breakage. This left 92 patients for analysis. RESULTS: Stem breakages were identified in 5.4% (five of 92) of patients. All stem breakages occurred in stem diameters 11 mm or less with a porous body construct; the percentage of patients with breakage in this group was 16% (five of 31). All patients with stem fracture demonstrated minimal ongrowth to the porous coated body. The median time to stem fracture was 10 years (range 2 to 12 years); however, two of the five stems broke within 3 years. CONCLUSION: We recommend the use of a larger-diameter GMRS cemented stem (> 11 mm), and either the line-to-line cementing method or an uncemented stem from an alternative company should be considered in order to achieve this larger stem in smaller canals. If a stem less than 12 mm in diameter must be used or there is evidence of minimal ongrowth, then close follow-up and prompt investigation of new symptoms should occur. LEVEL OF EVIDENCE: Level IV, therapeutic study.

Study on the effect of artificial joint replacement for osteosarcoma.

Osteosarcoma is one of the most prevalent primary malignant bone tumors that affects teenagers more than adults. In recent years, artificial femoral replacement has become more and more common. The use of artificial total femoral replacement surgery prevents the need for amputating the damaged limb, preserves the patient's ability to move and bear weight on the leg, lessens the severity of the psychological trauma, and significantly raises the patient's quality of life. To explore the treatment methods and therapeutic effects of artificial femoral replacement in the treatment of femoral osteosarcoma. The clinical data of 11 patients with femoral malignant tumors who underwent artificial femoral replacement from January 2019 to March 2022 were retrospectively analyzed. Among them, 7 males and 4 females, 11 to 40 years old, average 19.36 ± 9.44 years old. The disease duration is 2 to 7 months, with an average of 4.7 months. Before and 3 months after operation, the patients who had tumors were given a score on the visual analog scale, and their quality of life was also measured. At the most recent follow-up, both the Musculoskeletal Tumor Society score and the Harris hip score were analyzed. Eleven patients were followed up for 6 to 58 months, and an average of 21 months. Complications such as wound infection, joint dislocation, and nerve damage did not occur. In 1 patient, popliteal vein thrombus formation, and in 2 patients with osteosarcoma died from tumor progression. Visual analog scale score at 3 months after surgery and the quality-of-life scores were 3.68 ± 1.39 and 40.04 ± 4.31, respectively, which were significantly improved compared to before surgery (5.94 ± 1.19 and 22.42 ± 3.63, respectively, P < .05). At the last interview, Musculoskeletal Tumor Society score is scored from 18 to 29 points, average 22.5 ± 5.9 points, and Harris hip score is scored from 42 to 90 points, with an average score of 69.0 ± 14.7. Artificial total femoral replacement is an effective limb salvage operation in the treatment of osteosarcoma.

Megaprosthetic reconstruction of the distal femur with a short residual proximal femur following bone tumor resection: a systematic review.

BACKGROUND: To investigate the risk of postoperative function and complications associated with reconstruction methods in patients with short residual proximal femurs (< 12 cm) after resection of distal femoral bone tumors, we performed a systematic review of studies reporting postoperative function and complications in these patients. METHODS: Of the 236 studies identified by systematic searches using the Medline, Embase, and Cochrane Central Register of Controlled Trials databases, eight were included (none were randomized controlled trials). In these studies, 106 (68.4%), 12 (7.7%), and 37 (23.9%) patients underwent reconstruction with custom-made megaprostheses with extracortical plates or cross-pins, allograft prosthetic composite (APC), and Compress® compliant pre-stress (CPS) implants, respectively. RESULTS: Aseptic loosening occurred slightly more frequently in the APC group than in the other reconstruction methods (APC group, 21%; custom-made megaprosthesis group, 0-17%; CPS implant group, 14%). No differences were noted in the frequencies of implant breakage, fractures, or infections between the three reconstruction methods. Mechanical survival, where endpoint was set as implant removal for any reason, was 80% at seven years in the APC group, 70-77% at 10 years in the custom-made megaprosthesis group, and 68% at nine years in the CPS implant group. Therefore, there appeared to be no difference among the three reconstruction methods with respect to mechanical survival. CONCLUSIONS: During megaprosthetic reconstruction of the distal femur with a short residual proximal femur after bone tumor resection, similar results were obtained using custom-made megaprostheses, APCs, and CPS implants.

Rotationplasty after failed limb salvage: an alternative to amputation.

PURPOSE: Limb salvage procedures for musculoskeletal tumors have inherent complications. Though most complications can be managed with retention of the reconstructions, occasionally salvaging these reconstructions is not possible. We evaluated the outcomes of patients undergoing rotationplasty after multiple failed revisions of limb salvage surgery and document the success rate of this "salvage" technique and the subsequent functional outcome of these patients. METHOD: Between January 1, 1999, and December 31, 2018, 14 patients (12 male and 2 female) with a median age of 24 years (11-51 years) underwent rotationplasty after multiple failed revisions of limb salvage surgery. Indication for rotationplasty was infection (10 patients), failed megaprosthesis (2 patients), unstable biological reconstruction (1 patient) and local recurrence (1 patient). The mean number of surgeries done before the patient underwent rotationplasty was 5 (range 2-7). RESULTS: One patient developed a vascular complication (venous congestion) immediately after rotationplasty and underwent an early amputation. The remaining 13 patients had no surgical complications. Mean Musculo Skeletal Tumor Society score in 13 evaluable patients was 26 (23-30). CONCLUSION: Our study demonstrates the utility of rotationplasty as a "salvage" procedure after multiple failed lower limb salvage surgeries. It offers good success rates, low rates of complications and good functional outcomes in carefully selected cases.

Clinical Application of Artificial Intelligence: Auto-Discerning the Effectiveness of Lidocaine Concentration Levels in Osteosarcoma Femoral Tumor Segment Resection.

Adolescents and children worldwide are threatened by osteosarcoma, a tumor that predominantly affects the long bone epiphysis. Osteosarcoma is the most common and highly malignant bone tumor in youngsters. Early tumor detection is the key to effective treatment of this disease. The discovery of biomarkers and the growing understanding of molecules and their complex interactions have improved the outcome of clinical trials in osteosarcoma. This article describes biomarkers of osteosarcoma with the aim of positively influencing the progress of clinical treatment of osteosarcoma. Femoral bone tumor is a typical condition of osteosarcoma. Due to the wide range of femoral stem types, complexities in the distal femur, and tumors in the rotor part of femur, physicians following the traditional clinical approach face difficulties in removing the lesion and fixing the femur with resection of the tumor segment. In this paper, the effect of small doses of different concentrations of lidocaine anesthesia in patients undergoing lumpectomy for osteosarcoma femoral tumor segments is investigated. A computer-based artificial intelligence method for automated determination of different concentration levels of lidocaine anesthesia and amputation of osteosarcoma femoral tumor segment is proposed. Statistical analysis is carried on the empirical data including intraoperative bleeding, intraoperative and postoperative pain scores, surgical operation time, postoperative complications, patient satisfaction, and local anesthetic dose. The results showed that the patients in the study group had low intraoperative bleeding, short operation time, low postoperative hematoma formation rate, high patient satisfaction, higher dosage of anesthetic solution, and low dosage of lidocaine. Results revealed that mean arterial pressure and heart rate in extubating and intubating were significantly lower in the observation group than in the control group, and a significant difference (P < 0.05) was observed between the two groups. This proves that the proposed algorithm can adequately reduce bleeding, alleviate postoperative pain, shorten operation time, reduce complications, accelerate recovery, and ensure better treatment results.

Primary alveolar rhabdomyosarcoma of bone. / Rabdomiosarcoma alveolar primario de hueso. Reporte de un caso y revisión de la literatura.

INTRODUCTION: Rhabdomyosarcoma (RMS) is a malignant solid tumor of mesenchymal origin. It is the most com mon soft-tissue sarcoma in childhood and adolescence. 65% of cases are diagnosed before the age of 6. Histological subtypes include embryonal, alveolar, pleomorphic, and fused-cell RMS. The embryo nal subtype is more frequent in children, while the alveolar one is more frequent in adolescents and adults. OBJECTIVE: To describe the clinical presentation of primary alveolar rhabdomyosarcoma in a schoolgirl. CLINICAL CASE: 7-year-old schoolgirl with one-month history of progressive pain in her left thigh. X-ray shows a lytic lesion in the left femur diaphysis. A study was performed with 2 biopsies, immunohistochemistry, and PAX-FOXO1 studies which were compatible with alveolar RMS. Con clusion: Primary alveolar rhabdomyosarcoma of the bone is rare, but it should be considered within the differential diagnosis of primary small-round-blue cell bone tumors. Despite presenting a poor prognosis cytogenetic, this type of tumor seems to have better biological behavior, which for a successful treatment makes necessary to have a high index of suspicion in order to install a multimodal therapy in the context of a national protocol.

Novel fusion sarcomas including targetable NTRK and ALK.

BACKGROUND: Challenging emerging entities with distinctive molecular signatures may benefit from algorithms for diagnostic work-up. METHODS: Fusion sarcomas (2020-2021, during pandemic) were diagnosed by clinicoradiology, morphology, phenotype, and next-generation sequencing (NGS). RESULTS: Six fusion sarcomas in two males and four females involved the chest-wall, neck, or extremities; ages ranged 2-73, median 18 years. Sizes ranged 5.3-25.0, median 9.1 cm. These include high grade 1) TPR-NTRK1 of proximal femur with a larger rounded soft tissue mass, previously considered osteosarcoma yet without convincing tumor matrix. A pathologic fracture necessitated emergency hemipelvectomy (NED) and 2) novel KANK1-NTRK2 sarcoma of bone and soft tissue with spindled pleomorphic to epithelioid features (AWD metastases). 3) Novel ERC1-ALK unaligned fusion, a low grade infiltrative deep soft tissue hand sarcoma with prominent-vascularity, myopericytoid/lipofibromatosis-like ovoid cells, and collagenized stroma, was successfully treated with ALK-inhibitor (Crizotinib), avoiding amputation. These NTRK and ALK tumors variably express S100 and CD34 and were negative for SOX10. 4) and 5) CIC-DUX4 round cell tumors (rapid metastases/demise), one with COVID superinfection, were previously treated as Ewing sarcoma. These demonstrated mild pleomorphism and necrosis, variable myxoid change and CD99 reactivity, and a distinctive dot-like-Golgi WT1 immunostaining pattern. 6) A chest wall/thoracic round cell sarcoma, focal CD34/ keratins/CK7, revealed nuclear-STAT6, STAT6-NAB2 by NGS, confirming malignant solitary fibrous tumor, intermediate-risk-stratification (AWD metastases). CONCLUSIONS: Recent fusion sarcomas include new KANK1-NTRK2 and ERC1-ALK, the latter successfully treated by targeted-therapy. ALK/NTRK fusion partners TPR and KANK1 suggest unusual high-grade morphology/behavior. Clinicoradiologic, morphologic, and phenotypic algorithms can prompt molecular-targeted immunostains or NGS for final classification and promising inhibitor therapy.

Giant cell tumor of bone in an eighteenth-century Italian mummy.

Giant cell tumor (GCT) of the bone is a locally aggressive and rarely metastasizing neoplasm. It is composed of neoplastic mononuclear stromal cells with a monotonous appearance admixed with macrophages and osteoclast-like giant cells. In a small subset of cases, GCT is malignant. Terminology previously related to this entity, and which is no longer supported by the World Health Organization, includes osteoclastoma and benign fibrous histiocytoma (BFH). Giant cells occur in numerous other pathologic conditions of the bone, which accounts for the misrepresentation of these non-GCT tumors in the early literature. Non-ossifying fibroma (NOF), aneurysmal bone cyst, and chondroblastoma have been erroneously labeled GCT for this reason. A single description of an ancient GCT was reported by Brothwell and Sandison and subsequently mentioned by Aufderheide and Rodrìguez-Martìn who were astonished that more of these tumors had not been identified in archaeological cases. To the best of our knowledge, no other cases of ancient GCT have been cited in the paleopathology literature. The study of this type of neoplasm in antiquity can be used as a means to better understand its characteristics and behavior and to expand the depth of time of the etiology of these lesions. We report a case of GCT of the left femur observed following the total body CT imaging of a partially mummified adult female, dating to eighteenth century.

Utility of the ACS-NSQIP surgical risk calculator in predicting postoperative complications in patients undergoing oncologic proximal femoral replacement.

INTRODUCTION: Proximal femur replacement (PFR) in the setting of tumor resection is associated with a high rate of postoperative complication. The online American College of Surgeons-National Surgical Quality Improvement Program (ACS-NSQIP) surgical risk calculator is approved by the Center of Medicare and Medicaid services to estimate 30-day postoperative complications. This study was to determine if the ACS-NSQIP can predict postoperative complications following PFR. METHODS: We reviewed 103 (61 male and 42 female) patients undergoing PFR using the Current Procedural Terminology (CPT) codes available in the calculator: 27125 (hemiarthroplasty), 27130 (total hip), 27132 (conversion to total hip), 27134 (revision total hip), 27137 (revision acetabulum), 27138 (revision femur), and 27365 (excision tumor hip). The predicted rates of complications were compared with the observed rates. RESULTS: Complications occurred in 54 (52%) of patients, with the predicted risk based on CPT codes: 27125 (21.5%); 27130 (7.8%); 27132 (16.6%), 27134 (17.8%), 27137 (14.4%), 274138 (22.7%), and 27365 (16.2%). The calculator was a poor predictor of complications (27125, area under the curve [AUC] 0.576); (27130, AUC 0.489); (27132, AUC 0.490); (27134, AUC 00.489); (27137, AUC 0.489); (27138, AUC 0.471); and (27365, AUC 0.538). CONCLUSION: Oncologic PFR is known for complications. The ACS-NSQIP does not adequately predict the incidence of complications, and therefore cannot reliably be used in their shared decision-making process preoperative.

Variability in the reported surgical techniques and methods for intercalary reconstruction following tumor resection.

INTRODUCTION: There is currently no consensus regarding the best techniques or surgical strategies with which to maximize intercalary allograft reconstruction outcomes. The purpose of the current study was to assess which techniques and methods are being utilized by North American orthopaedic oncologists. METHODS: Members of the Musculoskeletal Tumor Society (MSTS) were invited to complete an anonymous online questionnaire. The survey presented participants with two clinical scenarios and interrogated them on their preferred type of allograft, method of compression and fixation, and additional techniques used. RESULTS: One hundred and twenty-six physicians completed the questionnaire. The majority studied in the United States (82%) and worked at an academic medical center (71%). Over half (54%) reported seeing over 10 primary bone tumors every year. Respondents were split between preferring a structural allograft alone or using a combined allograft-vascularized fibular graft. A majority indicated a preference for plate(s) and screw fixation but were divided between the use of two compression plates with a spanning plate, a single compression plate with a spanning plate, and two compression plates with an intramedullary nail. Screw fixation preferences were split between the use of unicortical locking only, bicortical locking only, and a combination of unicortical and bicortical locking. Almost equal percentages of respondents reported they would have used two, three, or four screws in both scenarios. Respondents were split between placing screws equidistantly and placing them peripherally within the allograft, adjacent to the allograft-host junction. DISCUSSION: There is no clear surgical preference for intercalary reconstruction following tumor extirpation within this sample of orthopaedic oncologists. The current survey demonstrates variability across nearly every aspect of allograft reconstruction, which may, in part, explain the wide spectrum of outcomes reported within the literature. Prospective studies are warranted to better evaluate technique-specific outcomes in an effort to maximize reconstructive longevity and minimize allograft related complications.

Is osseous reattachment of the greater trochanter necessary compared to soft-tissue-only abductor repair in proximal femoral megaprosthesis reconstruction?

BACKGROUND: One of the challenges to surgical reconstruction following oncologic proximal femur resection is reliable re-establishment of the abductor mechanism. Surgical and functional outcomes following re-approximation of the abductor mechanism to a metallic endoprosthetic after tumor resection of the proximal femur have not been well established in the literature. METHODS: A retrospective review was performed, inclusive of patients who received a proximal femur replacement with a metallic endoprosthesis following tumor resection. Patients were divided into two groups: (1) those that received an abductor repair involving a trochanteric osteotomy and osseous fixation of the greater trochanter/abductor mechanism to the endoprosthesis, and (2) those that did not have a trochanteric osteotomy and therefore had an abductor repair consisting of only soft tissue reattachment to the endoprosthesis. The two groups were assessed for demographic characteristics, diagnosis, surgical outcomes including rates of complication and failure, radiographic evidence of trochanteric failure, and functional outcomes. Descriptive statistics, comparative statistics, and logistic regression analyses were performed to discern differences between the two study groups. RESULTS: Fifty-three patients were included in the analysis, 29 had abductor reconstructions involving reattachment of the greater trochanter to the metallic endoprosthesis and 24 had soft tissue reconstruction of the abductor mechanism without bony fixation. There were no differences between the two groups for demographic data, cancer diagnosis, follow up, or survivorship. Radiographic evidence of trochanteric dissociation from the endoprosthesis was observed in 45% of osteotomy cases. Only 10% of patients in the trochanter osteotomy group and 38% of the soft tissue only group were able to resume a normal, non-Trendelenburg gait at final postoperative visit (p = .024). Need for an assistive ambulatory device was seen in 83% and 67% of the osteotomy and soft-tissue-only patients, respectively (p = .21). CONCLUSION: Re-establishing the abductor mechanism following proximal femur oncologic resection remains a challenge to orthopedic oncologists. Even when possible, salvage of the greater trochanter for reattachment to the endoprosthesis did not lead to improved function in this series, when compared to a similar cohort that received a soft-tissue-only abductor repair. Abductor mechanism reconstruction with a greater trochanteric osteotomy and subsequent fixation to the proximal femur endoprosthesis had a high rate of radiographic failure. Additionally, reattachment of the greater trochanter to the proximal femur endoprosthesis demonstrated no improvement in Trendelenburg gait or reliance on an assistive ambulatory device when compared to a soft-tissue-only abductor repair.

Role of PRPS2 as a prognostic and therapeutic target in osteosarcoma.

AIMS: Osteosarcoma (OS) is the most common primary malignant tumour of the bone. However, further improvement in survival has not been achieved due to a lack of well-validated prognostic markers and more effective therapeutic agents. Recently, the c-Myc-phosphoribosyl pyrophosphate synthetase 2 (PRPS2) pathway has been shown to promote nucleic acid metabolism and cancer cell proliferation in malignant melanoma; phosphorylated mammalian target of rapamycin (p-mTOR) has been upregulated and an effective therapeutic target in OS. However, the p-mTOR-PRPS2 pathway has not been evaluated in OS. METHODS: In this study, the expression level of PRPS2, p-mTOR and marker of proliferation (MKI-67) was observed in a cohort of specimens (including 236 OS cases and 56 control samples) using immunohistochemistry, and the association between expression level and clinicopathological characteristics of patients with OS was analysed. RESULTS: PRPS2 protein level, which is related to tumour proliferation, was higher in OS cells (p=0.003) than in fibrous dysplasia, and the higher PRPS2 protein level was associated with a higher tumour recurrence (p=0.001). In addition, our statistical analysis confirmed that PRPS2 is a novel, independent prognostic indicator of OS. Finally, we found that the expression of p-mTOR was associated with the poor prognosis of patients with OS (p<0.05). CONCLUSIONS: PRPS2 is an independent prognostic marker and a potential therapeutic target for OS.

Co-existence of lung carcinoma metastasis and enchondroma in the femur of a patient with Ollier disease.

Tumour-to-tumour metastasis is very unusual and has been defined as a tumour metastasis into another histologically different tumour. It is extremely rare in bone. We report a case of lung squamous cell carcinoma metastasized to an enchondroma in the femur of a patient with Ollier disease. A 60-year-old female had a history of a poorly differentiated squamous cell carcinoma of the lung. She underwent a video-assisted thoracoscopic lobectomy, and a follow-up MRI scan showed three lesions in the left distal femur and proximal tibia, which were initially interpreted as metastasis on radiology. Resection of the left proximal tibial lesion was performed, and the pathological findings were consistent with enchondroma with no evidence of metastasis. Subsequent curettage of lesions in the distal left femur revealed metastatic poorly differentiated carcinoma with foci of hyaline cartilage, which was most consistent with metastatic carcinoma in a pre-existing enchondroma. The MRI films were re-reviewed. Characteristic MRI features of enchondroma were found in the lesion in the left proximal tibia and one of the lesions in the left distal femur, while the features of the other lesion in the left distal femur included cortical destruction and extensive oedema in surrounding soft tissue, which were consistent with a malignant tumour. In addition, the enchondroma in the lateral condyle showed blurring and irregular inner margin and adjacent bone oedema, which likely represents a co-existing metastatic tumour and enchondroma. The difference in lineage was confirmed by immunohistochemistry. The final diagnosis was metastatic poorly differentiated carcinoma of the lung into a co-existent enchondroma. The diagnosis can be challenging and could be easily overlooked both radiologically and histologically. Thorough clinical and radiological information is critical for the diagnosis, and despite a very unusual event, awareness of the tumour-to-tumour metastasis phenomenon can avoid an inaccurate diagnosis by the pathologist, therefore preventing inappropriate clinical intervention.

Comparison of all-polyethylene and metal-backed modular tibial components in endoprosthetic reconstruction of the distal femur.

INTRODUCTION: All-polyethylene (AP) tibial components have demonstrated equivalent or improved long-term survivorship and reduced cost compared with metal-backed (MB) components in primary total knee arthroplasty; however, there is a lack of data comparing these outcomes in the setting of an oncologic endoprosthetic reconstruction. METHODS: A total of 115 (88 AP:27 MB) patients undergoing cemented distal femur endoprosthetic reconstruction following oncologic resection were reviewed. Mean age was 40 years and 51% were females. Cumulative incidences of all-cause revision, tibial component revision, reoperation, and infection were calculated utilizing a competing risk analysis with death as the competitor. Mean follow-up was 14 years. RESULTS: The 10-year cumulative incidence of all-cause revision was 19.9% in the AP group and 16.3% in the MB group (hazard ratio [HR] = 0.93, p = 0.88). The cumulative incidence of tibial component revision was significantly lower in AP compared with MB at 10 years (1.1% vs. 12.5%, HR = 0.18, p = 0.03). There was no difference in infection-free survival when comparing the two groups (p = 0.72). CONCLUSIONS: Reconstruction utilizing an MB or AP tibia component resulted in equivalent overall outcome; however, the tibial component in the AP group was less likely to be revised. AP tibial component should be considered for all primary oncologic reconstructions in the distal femur. LEVEL OF EVIDENCE: Level III Therapeutic.

High-Grade Sarcoma Arising in Association With an Intraosseous Lipoma: A Case Report.

CASE: A 78-year-old man was followed for an incidentally found, asymptomatic lesion in his right proximal femur that was unchanged radiographically for 11 years. He developed pain and was believed to have experienced a stress fracture through the lesion. The lesion was biopsied, showing a high-grade pleomorphic sarcoma with an underlying senescent intraosseous lipoma. He was ultimately treated with wide excision and reconstruction of the proximal femur. CONCLUSION: This case highlights the importance of obtaining a tissue diagnosis for lesions that become symptomatic.

Prediction of pathological fracture in patients with lower limb bone metastasis using computed tomography imaging.

Lower limb pathological fractures caused by bone metastases can severely impair activities of daily living, so recognizing fracture risk is essential. Medial cortical involvement (MCI) in the proximal femur has been demonstrated to affect bone strength in biomechanical studies, but it has not been investigated in real patients. Between 2012 and 2019, 161 bone metastases with computed tomography (CT) images were retrospectively examined. Twenty-nine fractures were observed including 14 metastases with pathological fractures at the first examination, and prophylactic surgery was performed for 50 metastases. We extracted clinicopathological data using CT images, including patient's background, MCI in the proximal femur, site, size, circumferential cortical involvement (CCI), pain, and nature of metastasis. Cox proportional hazard regression analyses were performed, and we created integer scores for predicting fractures. We revealed that MCI, CCI, lytic dominant lesion, and pain were significant factors by univariate analyses. By multivariable analysis, MCI and each 25% CCI were significant and integer score 1 was assigned based on hazard ratio. The full score was four points, with MCI in the proximal femur (one point) and ≥ 75% CCI (three points). With integer score two, sensitivity was 88.9% and specificity was 81.2% for predicting fracture within 60 days. In conclusion, MCI and CCI examined by CT images were the risk factors for pathological fracture. CCI ≥ 50% is a widely known risk factor, but in addition, it may be better to consider surgery if MCI in the proximal femur is observed in metastasis with 25-50% CCI.

Very late relapse of high-grade osteosarcoma: A case report and review of the literature.

RATIONALE: Osteosarcoma is the most common primary malignant bone tumor in children. The prognosis of osteosarcoma has improved with the use of aggressive systemic chemotherapy in addition to surgery. The relapse of osteosarcomas is usually as lung metastasis observed within 2 to 3 years after the initial treatment. A relapse is rarely observed at >10 years. PATIENT CONCERNS: We report the case of a 51-year-old Japanese man who was treated for high-grade osteosarcoma of the femur at 13 years old. He was referred to our hospital with a suspicion of primary lung cancer based on back pain, respiratory distress, and an abnormal mass on chest radiograph. DIAGNOSES: Computed tomography-guided biopsy confirmed the lung lesion as a metastatic recurrence of high-grade osteosarcoma without local recurrence. INTERVENTIONS: Chemotherapy was planned, but the patient's general condition rapidly deteriorated and thus palliative therapy was provided. OUTCOMES: The patient died 2 months after the initial consultation. LESSONS: The survival durations of osteosarcoma patients have been prolonged by recent progress in multimodality therapy, and thus clinicians as well as osteosarcoma patients should always keep in mind the possibility of very late relapse.

Parosteal Osteosarcoma: A Benign-Looking Tumour, Amenable to a Variety of Surgical Reconstruction.

Osteosarcoma arising from cortical surface is classified into parosteal, periosteal and high-grade surface osteosarcoma. Along the spectrum, parosteal osteosarcoma occupies the well-differentiated end. It is a relatively rare disease entity, comprised only 4% of all osteosarcomas and barely reported in the literature. The objective of this study is to describe cases of parosteal osteosarcoma as well as a variety of treatment options amenable to such entity. Six cases of parosteal osteosarcoma were identified based on histopathological reports in a tertiary referral hospital in Jakarta, Indonesia between January 2001 and December 2019. The mean age was 29.8 years old; four of them (66.7%) were male. Distal end of femur was the most commonly involved bone (five cases, 83.3%). The patients were treated with wide excision followed by several different reconstruction methods: replacement with endoprosthesis, extracorporeal irradiation, knee arthrodesis, or prophylactic fixation. One of our patients presented with dedifferentiated component, and therefore was treated by limb ablation. While two cases died of pulmonary metastasis, other patients reported fair to excellent functional outcome.