Slipped capital femoral epiphysis after tumor prosthesis implantation in a patient receiving chemotherapy.

While the usual etiology of slipped capital femoral epiphysis (SCFE) is idiopathic, there are many other factors that increase the predisposition to slippage. Chemotherapy can be one of them. In this article, we report a rare case of acute SCFE after tumor prosthesis implantation in a patient who received chemotherapy. A 10-year-old girl with osteosarcoma of the right distal femur underwent (neo-) adjuvant chemotherapy, wide tumor resection, and reconstruction using a growing tumor prosthesis and a short non-cemented femoral stem. Half a year after implantation, she developed aseptic loosening. Revision surgery was performed using a hydroxyapatite (HA)-coated cementless femoral stem. Postoperative plain radiographs revealed SCFE that was treated by closed reduction and screw fixation. The patient recovered without complications, and unaffected hip showed no radiographic signs of slippage on follow-up. The forces of implanting a tumor prosthesis, particularly with a non-cemented stem, can increase the risk of an acute SCFE. The controversy over prophylactic pinning of the uninvolved hip in chemotherapy-associated SCFE is unresolved. Pinning can be considered only in the presence of abnormal prodromal radiological findings.

Parosteal osteosarcoma with low grade chondrosarcoma and liposarcoma components. A rare histologic variant. Case report and literature review.

INTRODUCTION: conventional parosteal osteosarcoma is an uncommon malignant bone tumor, comprising 4% of all osteosarcomas. Although rare, parosteal osteosarcoma is the most common type of osteosarcoma of the bone surface. We present the clinical, histological and imaging characteristics of a rare histologic variant of a parosteal osteosarcoma, review the literature and emphasize the importance of radio-pathological correlation as well as the interpretation of a representative biopsy in order to obtain the correct diagnosis. CASE REPORT: a 36-year old woman began her condition one year prior to admission to the hospital with increased volume in the left knee and pain. Image studies showed a juxtacortical heterogeneous tumor localized on the posterior surface of the distal femoral metaphysis. An incisional biopsy was performed, with the diagnosis of a Parosteal Osteosarcoma and a wide surgical resection was undertaken. According to the findings of the surgical specimen, the diagnosis of a Parosteal Osteosarcoma with low grade chondrosarcoma and liposarcoma components was made. The knowledge of this rare parosteal osteosarcoma variant can lead the orthopedic oncologists to avoid overlooking the adipose component and provide adequate surgical margins. CONCLUSION: we present the clinical, histological and imaging characteristics of a Parosteal Osteosarcoma with low grade liposarcoma and chondrosarcoma components.

INTRODUCCIÓN: el osteosarcoma parosteal convencional es un tumor óseo maligno poco común, que comprende el 4% de todos los osteosarcomas. Aunque es poco común, el osteosarcoma parosteal es el tipo más común de osteosarcoma de la superficie ósea. Presentamos las características clínicas, histológicas y de imagen de una variante histológica rara de un osteosarcoma parosteal, revisamos la literatura y enfatizamos la importancia de la correlación radio-patológica, así como la interpretación de una biopsia representativa para obtener el diagnóstico correcto. REPORTE DE CASO: mujer de 36 años inició su cuadro un año antes de su ingreso al hospital con aumento de volumen en rodilla izquierda y dolor. Los estudios de imagen mostraron una tumoración heterogénea yuxtacortical localizada en la superficie posterior de la metáfisis femoral distal. Se realizó biopsia incisional, con diagnóstico de osteosarcoma parosteal y se realizó resección quirúrgica amplia. De acuerdo con los hallazgos de la pieza quirúrgica se realizó el diagnóstico de osteosarcoma parosteal con componentes de condrosarcoma y liposarcoma de bajo grado. El conocimiento de esta rara variante de osteosarcoma parosteal puede llevar a los ortopedistas oncólogos a considerar otros componentes y proporcionar márgenes quirúrgicos adecuados. CONCLUSIÓN: presentamos las características clínicas, histológicas y de imagen de un osteosarcoma parosteal con componentes de liposarcoma y condrosarcoma de bajo grado.

A Successful Clinical Outcome 29 Months Following Improper Placement of the Compress Implant: A Case Report.

CASE: A 24-year-old woman presented with dedifferentiated parosteal osteosarcoma of the proximal femur and was treated with limb salvage surgery using the Compress implant. It was implanted with a technical error, was not revised, and has demonstrated no negative outcomes 29 months postoperatively. CONCLUSION: An instance of incorrect pin placement during the implantation of a Zimmer Compress implant is presented with good survivorship. This report acts as information for other surgeons who might inadvertently obtain unicortical fixation. In this patient, revision surgery was avoided and an excellent, short-term outcome was achieved while avoiding the potentially devastating complications associated with revision implantation.

3D-printed Multifunctional Guide Plate for Fenestration and Screws Drill in Proximal Femoral Benign Tumor.

The accurate fenestration, screw implantation and assisting stabilizing-plate placement in surgery of benign tumors in the proximal femur needs be defined easily. The aim of this study was to investigate the value of 3D printed multifunctional guides plate (3D-MGP) based on computer aided design. Between January 2020 and June 2022, 17 patients (nine females and eight males) with benign proximal femoral tumor had lesion curettage and allograft combined with internal plate fixation using 3D-MGP. In this study, the patients had CT scans and a technician reconstructed the 3D images of tumor and the femur, a doctor designed the location and margin of the fenestration and screws, and integrated different functions into MGP for benign proximal femoral lesions, which assisted in precise localization, fenestration and screw drilling. Musculoskeletal Tumor Society (MSTS) scoring was used to evaluate lower extremity function. Bone healing and the screws location was assessed with the radiographs. All patients underwent successful surgery with complete resection of the tumor and internal fixation with using the 3D-MGP. The mean follow-up was 16.4 months. The operative time was 126.47 ± 18.44 min, intraoperative bleeding was 198.23 ± 67.94 mL, intraoperative fluoroscopy was 6.47 ± 0.62, postoperative drainage was 223.82 ± 119.51 mL, and MSTS score was 27.29 ± 1.31 points. There were no unplanned fenestration and improper screw fixation. The 3D-MGP enabled personalized and accurate location of tumor, fenestration, screw placement and assisted stabilizing-plate placement for the treatment of benign tumor of the proximal femur. This technique has the potential to shorten operative times, decrease intraoperative bleeding, and reduce radiation exposure to patients.

Hip Preservation and Capanna Reconstruction for Pediatric Proximal Femur Ewing Sarcoma: A Report of 2 Cases.

CASE: This is a first report describing preservation of the femoral head by transcervical resection of proximal femoral Ewing sarcoma in 2 pediatric patients. A unique Capanna reconstruction supported joint salvage. At 1 year, Pediatric Outcomes Data Collection Instrument and Pediatric Toronto Extremity Salvage Score outcomes were excellent. Surveillance magnetic resonance imaging was without evidence of recurrence or impaired perfusion to the femoral head. CONCLUSION: We demonstrate the feasibility of hip joint preservation and maintenance of femoral head viability after transcervical resection of pediatric proximal femur bone sarcomas while preserving the medial circumflex femoral artery. This technique may be a preferred option over joint sacrifice and endoprosthetic replacement in young patients when tumor margins permit.

Risk of complications and implant survival of surgical treatment of proximal femoral metastasis: a meta-analysis.

PURPOSE: The patients with femoral metastasis in the inter- or subtrochanteric area could be treated with intramedullary nailing or prosthetic reconstruction, however, it is controversial which surgical treatment could offer less complications and implant failure. Our purpose was to define the risk of complications and implant survival in patients treated with intramedullary nailing or prosthetic reconstruction. METHODS: We analyzed studies reporting the risk of complications, reoperations and removal of the implant in patients treated with intramedullary nailing, hemiarthroplasty, arthroplasty or megaprosthesis. RESULTS: We analyzed 27 studies (1346 patients) reporting patients treated with intramedullary nail (51%), hemiarthroplasty (15%), arthroplasty (2%), megaprosthesis with (25%) or without (7%) acetabular component. No difference was found in the overall risk of complications between patients treated with intramedullary nailing 6%, hemiarthroplasty or total hip arthroplasty 7% and megaprosthesis 11% (p = 0.23). However, patients treated with megaprosthesis had increased risk of reoperation due to infection (70%), compared to the patients treated with intramedullary nail (13%), and patients treated with hemiarthroplasty or total hip arthroplasty (23%) (p = 0.02). Revision due to disease progression was required in 61% of the patients treated with intramedullary nail, but not in patients treated with hemiarthroplasty, total arthroplasty, and megaprosthesis (p = 0.03). CONCLUSION: Patients treated with megaprosthesis had higher risk of reoperation due to infection, while patients treated with intramedullary nailing had higher risk of revision due to disease progression. Regarding patients treated with megaprosthesis, the risk of reoperation due to dislocation was higher in those treated with acetabular component.

Management of Ipsilateral Fractures After Rotationplasty: A Report of 2 Cases and Review of the Literature.

CASE: Rotationplasty is a surgical procedure used for restoring functionality after skeletal tumor resection. Multiple complications have been described, including the potential occurrence of fractures. Literature on fracture management after rotationplasty is limited. In this article, we present 2 cases of late ipsilateral fractures in rotated limbs successfully treated with intramedullary nailing. CONCLUSION: Effective management of fractures after rotationplasty requires thorough understanding of the rotated limb anatomy and careful planning. The clinical considerations presented in this article aim to provide guidance for surgeons to achieve successful outcomes in the management of fractures after rotationplasty.

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.

What are the indications and survivorship of tumor endoprosthetic reconstructions for patients with extremity metastatic bone disease?

BACKGROUND AND OBJECTIVES: Given advances in therapies, endoprosthetic reconstruction (EPR) in metastatic bone disease (MBD) may be increasingly indicated. The objectives were to review the indications, and implant and patient survivorship in patients undergoing EPR for MBD. METHODS: A review of patients undergoing EPR for extremity MBD between 1992 and 2022 at two centers was performed. Surgical data, implant survival, patient survival, and implant failure modes were examined. RESULTS: One hundred fifteen patients were included with a median follow-up of 14.9 months (95% confidence interval [CI]: 9.2-19.3) and survival of 19.4 months (95% CI: 13.6-26.1). The most common diagnosis was renal cell carcinoma (34/115, 29.6%) and the most common location was proximal femur (43/115, 37.4%). Indications included: actualized fracture (58/115, 50.4%), impending fracture (30/115, 26.1%), and failed fixation (27/115, 23.5%). Implant failure was uncommon (10/115, 8.7%). Patients undergoing EPR for failed fixation were more likely to have renal or lung cancer (p = 0.006). CONCLUSIONS: EPRs were performed most frequently for renal cell carcinoma and in patients with a relatively favorable survival. EPR was indicated for failed previous fixation in 23.5% of cases, emphasizing the importance of predictive survival modeling. EPR can be a reliable and durable surgical option for patients with MBD.

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.

Reconstruction of massive bone defects after femoral tumor resection using two new-designed 3D-printed intercalary prostheses: a clinical analytic study with the cooperative utilization of multiple technologies.

BACKGROUND: To reconstruct massive bone defects of the femoral diaphysis and proximal end with limited bilateral cortical bone after joint-preserving musculoskeletal tumor resections, two novel 3D-printed customized intercalary femoral prostheses were applied. METHODS: A series of nine patients with malignancies who received these novel 3D-printed prostheses were retrospectively studied between July 2018 and November 2021. The proximal and diaphyseal femur was divided into three regions of interest (ROIs) according to anatomic landmarks, and anatomic measurements were conducted on 50 computed tomography images showing normal femurs. Based on the individual implant-involved ROIs, osteotomy level, and anatomical and biomechanical features, two alternative 3D-printed prostheses were designed. In each patient, Hounsfield Unit (HU) value thresholding and finite element analysis were conducted to identify the bone trabecula and calcar femorale and to determine the stress distribution, respectively. We described the characteristics of each prosthesis and surgical procedure and recorded the intraoperative data. All patients underwent regular postoperative follow-up, in which the clinical, functional and radiographical outcomes were evaluated. RESULTS: With the ROI division and radiographic measurements, insufficient bilateral cortical bones for anchoring the traditional stem were verified in the normal proximal femur. Therefore, two 3D-printed intercalary endoprostheses, a Type A prosthesis with a proximal curved stem and a Type B prosthesis with a proximal anchorage-slot and corresponding locking screws, were designed. Based on HU value thresholding and finite element analysis, the 3D-printed proximal stems in all prostheses maximally preserved the trabecular bone and calcar femorale and optimized the biomechanical distribution, as did the proximal screws. With the 3D-printed osteotomy guide plates and reaming guide plates, all patients underwent the operation uneventfully with a satisfactory duration (325.00 ± 62.60 min) and bleeding volume (922.22 ± 222.36 ml). In the follow-up, Harris Hip and Musculoskeletal Tumor Society scores were ameliorated after surgery (P < 0.001 and P < 0.001, respectively), reliable bone ingrowth was observed, and no major complications occurred. CONCLUSIONS: Two novel 3D-printed femoral intercalary prostheses, which achieved acceptable overall postoperative outcomes, were used as appropriate alternatives for oncologic patients with massive bone defects and limited residual bone and increased the opportunities for joint-preserving tumor resection. Several scientific methodologies utilized in this study may promote the clinical design proposals of 3D-printed implants.

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.

Survival and failure modes of the Compress® spindle and expandable distal femur endoprosthesis among pediatric patients: A multi-institutional study.

BACKGROUND: Expandable endoprostheses can be used to equalize limb length for pediatric patients requiring reconstruction following large bony oncologic resections. Outcomes of the Compress® Compliant Pre-Stress (CPS) spindle paired with an Orthopedic Salvage System expandable distal femur endoprosthesis have not been reported. METHODS: We conducted a multi-institutional retrospective study of pediatric patients with distal femoral bone sarcomas reconstructed with the above endoprostheses. Statistical analysis utilized Kaplan-Meier survival technique and competing risk analysis. RESULTS: Thirty-six patients were included from five institutions. Spindle survivorship was 86.3% (95% confidence interval [CI], 67.7-93.5) at 10 years. Two patients had a failure of osseointegration (5.7%), both within 12 months. Twenty-two (59%) patients had 70 lengthening procedures, with mean expansions of 3.2 cm (range: 1-9) over 3.4 surgeries. The expandable mechanism failed in eight patients with a cumulative incidence of 16.1% (95% CI, 5.6-31.5) at 5 years. Twenty-nine patients sustained International Society of Limb Salvage failures requiring 63 unplanned surgeries. Periprosthetic joint infection occurred in six patients (16.7%). Limb preservation rate was 91% at 10 years. CONCLUSIONS: There is a high rate of osseointegration of the Compress® spindle among pediatric patients when coupled with an expandable implant. However, there is a high rate of expansion mechanism failure and prosthetic joint infections requiring revision surgery. LEVEL OF EVIDENCE: Level IV, therapeutic study.

Application of the Locking Compression Pediatric Hip Plate™ in children with proximal femoral tumors.

BACKGROUND: Pediatric proximal femoral tumors often present with accumulative and severe bone destruction and are often complicated by pathological fractures and malunion. Such tumors are treated clinically by lesion scraping and graft reconstruction with autologous iliac bone alone or in combination with artificial bone. This study aimed to determine the efficacy of the Locking Compression Pediatric Hip Plate™ in treating pediatric proximal femoral tumors. METHODS: From 2012-2017, the Locking Compression Pediatric Hip Plate™ was applied for internal fixation in 28 children in the Department of Pediatric Surgery. The complications were pathological fractures in 19 patients and multiple lesions in 5 patients. Tumors were removed by tumor curettage and reconstruction with autogenous iliac bone or artificial bone graft. The Locking Compression Pediatric Hip Plate™ was then applied. Postoperative pathological examination confirmed the diagnosis. RESULTS: The cohort comprised 20 males and 8 females (mean age 7.8 ± 2.9 years). The mean follow-up duration was 26.1 ± 8.1 months (range 18-48 months). Post-treatment radiography showed that the lesions and local pathological fractures were healed in 3.2 ± 0.4 months (range 3-4 months), with no complications. Four patients continued to receive antineoplastic therapy postoperatively. Four patients experienced recurrence in situ, while another four developed distant metastases. The radiographic and joint function findings indicated that the affected limbs had excellent function. The mean Enneking score was 28.7 ± 1.0 points (range 27-30 points). CONCLUSIONS: Internal fixation with the Locking Compression Pediatric Hip Plate™ in children achieves good therapeutic effects. Moreover, the Locking Compression Pediatric Hip Plate™ resolves the shortcomings of external fixation by traditional plaster casts and internal fixation by Kirschner wires and elastic intramedullary screws.

[Application of three-dimensional printed customized prosthesis with preserved epiphysis and articular surface in the reconstruction of large bone defects in treatment of adolescent femoral malignant tumors].

Objective: To investigate the clinical application and effectiveness of three-dimensional (3D) printed customized prosthesis with preserved epiphysis and articular surface in the reconstruction of large bone defects in treatment of adolescent femoral malignant tumors. Methods: The clinical data of 10 adolescent patients with femoral primary malignant tumor who met the selection criteria and underwent limb salvage surgery with 3D printed customized prosthesis with preserved epiphysis and articular surface between January 2020 and October 2021 were retrospectively analyzed. There were 6 males and 4 females with an average age of 12.5 years ranging from 7 to 18 years. There were 8 cases of osteosarcoma and 2 cases of Ewing's sarcoma. Enneking stage was Ⅱb. The length of the lesions ranged from 76 to 240 mm, with an average of 138.0 mm. The length of osteotomy (i. e. length of customized prosthesis) ranged from 130 to 275 mm, with an average of 198.5 mm; the distance between distal osteotomy end and epiphyseal line ranged from 0 to 15 mm, with an average of 8.8 mm; the bone defect after osteotomy accounted for 37.36% to 79.02% of the total length of the lesion bone, with a mean of 49.43%. The operation time, intraoperative blood loss, complications, tumor outcome (refered to RESIST1.1 solid tumor efficacy evaluation criteria), and limb length discrepancy were recorded. The Musculoskeletal Cancer Society (MSTS) 93 score was used to evaluate the function at 6 months after operation, and visual analogue scale (VAS) score was used to evaluate the pain before and after operation. Results: The operation was successfully performed in all the 10 patients, and the postoperative pathological results were consistent with the preoperative pathological results. The operation time was 165-440 minutes, with an average of 263 minutes; and the intraoperative blood loss was 100-800 mL, with an average of 350 mL. All patients were followed up 7-26 months, with an average of 11.8 months. No tumor was found on the osteotomy surface; the customized prosthesis were firmly installed and closely matched with the retained articular surface. The tumor outcome of neoadjuvant chemotherapy was stable in 4 cases and partial remission in 6 cases. No local recurrence or distant metastasis was found in 9 cases after postoperative adjuvant chemotherapy; pulmonary metastasis was found in 1 case at 12 months after operation. Two patients had local incision fat liquefaction, superficial infection, and delayed healing at 14 days after operation; 1 patient had local bone absorption at the contact surface of the prosthesis, and the screw and prosthesis did not loosen at 7 months after operation; the other patients had good incision healing, with no infection, prosthesis loosening, fracture, or other complications. At 6 months after operation, the MSTS93 score was 19-28, with an average of 24.1; 8 cases were excellent and 2 cases were good. The VAS score was 0.9±1.0, which significantly improved when compared with before operation (5.9±1.0) ( t=23.717, P<0.001). The height of the patients increased by 1-12 cm, with an average of 4.6 cm. At last follow-up, 4 patients had limb length discrepancy, with a length difference of 1 cm in 2 cases and 2 cm in 2 cases. Conclusion: The application of 3D printed customized prosthesis in the resection and reconstruction of adolescents femoral primary malignant tumors can achieve the purpose of preserving epiphysis and articular surface, and obtain good effectiveness.

Modified Borggreve-Van Nes-Winkelmann rotationplasty for surgery in developing countries.

BACKGROUND: Amputation is still the most common therapy for patients suffering from osteosarcoma in Myanmar, despite the fact that limb salvage surgery e.g. Borggreve-Van Nes-Winkelmann rotationplasty for malignant tumors located within the distal femur or proximal tibia is the current state-of-the-art reconstructive procedure. A safe and reliable operation technique is crucial in order to perform a complex surgical procedure like the rotationplasty in lower-middle income economies with limited infrastructure and resources. The authors present seven cases of patients with osteosarcomas that received a Borggreve-Van Nes-Winkelmann rotationplasty with an evaluation of the procedures focusing on safety and sustainability. METHODS: From 2019 until 2020, seven young patients with osteosarcomas of the distal femur or proximal tibia were treated with Borggreve-Van Nes-Winkelmann rotationplasties in the Orthopaedic Hospital in Mandalay, Myanmar. As modification of the standard procedure the dissection and subsequent clamping of the femoral artery in order to minimize blood loss as well as the formation of an adipocutaneous flap that minimizes swelling and decreases the pressure on the vessels were successfully performed. This modified procedure resembles a safe and simplified surgical technique that is feasible under the circumstances of lower-middle income economies with good outcomes. RESULTS: All patients showed good functional and aesthetic results. One of the seven patients needed secondary wound closure due to wound dehiscence. CONCLUSIONS: A simplified and safe operation technique for the performance of the Van Nes-Borggreve rotationplasty was adapted to the given constraints in lower-middle income economies and proved to be successful. Trial registration All patients approved to participate in the study and have given consent to publication.

Cementless curved endoprosthesis stem for distal femoral reconstruction in a Chinese population: a combined anatomical & biomechanical study.

BACKGROUND: The endoprosthetic knee reconstruction using a current universal femoral stem might not be suitable for local population due to the anatomical difference between Chinese and Western populations. We measured the anatomical parameters of Chinese femurs as reference for stem design, and proposed a cementless, curved, short endoprosthesis stem for the reconstruction of distal femur. This study analyzed the biomechanical performance of the newly designed stem aimed at the identification of better operative strategy. METHODS: The CT-scanning data of femurs derived from 96 healthy Chinese volunteers were imported into the Mimics software, and a segmental measurement strategy was applied to evaluate the radius of curvature (ROC) of the femoral medullary cavity. Then, 4 kinds of endoprosthetic replacement models were created based on the measurement results. Model A: the distal tumor resected femora + straight stem A; Model B: the distal tumor resected femora + curved stem B; Model C: the distal tumor resected femora + curved stem C; Model D: the distal tumor resected femora + curved stem D. Finally, the mechanical difference among these models were compared by finite element analysis. RESULTS: The mean femoral ROC of Segment1, 2, 3, 4, 5 measured in the present study was 724.5 mm, 747.5 mm, 1016.5 mm, 1286.5 mm, and 1128 mm, respectively. Based on the femoral ROC of Segment2, the stem ROC of the curved stem B, C, and D was designed as 475 mm, 700 mm, and 1300 mm, respectively. Generally, all endoprosthetic replacement models showed a normal-like stress distribution on the femurs. However, compared to the straight stem, the biomimetic curved stem showed better biomechanical performance both in terms of reducing the extent of the stress shielding of the femur and in terms of minimizing the stress distribution of the implant. CONCLUSIONS: The uncemented, curved, short stem with suitable ROC can perfectly match the Chinese femoral canal morphology which has better mechanical properties than the conventional femoral stem. Thus, this newly designed femoral stem might be an optimized method for treatment of malignant femoral tumours in the Chinese populations in the case that the numerical results are supported by future experimental studies.