Long-term effects of retrograde approach on the knee after motorized femoral limb lengthening.

BACKGROUND AND PURPOSE: The retrograde femoral approach is an established technique for implantation of nails for leg lengthening and correction and in cases of distal femoral fractures. The purpose of this study was to determine the 10-year outcome of this technique by analyzing the clinical long-term effects and radiological status of the knee after leg lengthening via a retrograde femoral approach. PATIENTS AND METHODS: This retrospective single-center study included 13 patients (median age at surgery 17 [range 15-20] years) who underwent unilateral, retrograde, femoral lengthening with a motorized nail. Outcome measurements were graded variables of the SF-36, ISKD score, and Lysholm score. MRI of both knees was performed in all patients. MRI was evaluated for the presence of degenerative changes and compared with the healthy contralateral knee. Cartilage condition was graded according to the International Cartilage Repair Society (ICRS) scoring system. RESULTS: All patients were pain-free and had a full range of motion 10 (range 10.0-12.2) years after surgery. All postoperative knees showed fibrosis of Hoffa's fat pad and moderate to severe cartilage defects (ICRS Grade 2-4) of the trochlear groove (nail entry site). 6 out of 13 operated knees exhibited retropatellar cartilage defects. CONCLUSION: Our study showed that patients were pain-free, but cartilage defects at the entry point and arthrofibrosis at Hoffa's fat pad were observed without causing clinical impairment.

Methylation and copy number profiling: emerging tools to differentiate osteoblastoma from malignant mimics?

Rearrangements of the transcription factors FOS and FOSB have recently been identified as the genetic driver event underlying osteoid osteoma and osteoblastoma. Nuclear overexpression of FOS and FOSB have since then emerged as a reliable surrogate marker despite limitations in specificity and sensitivity. Indeed, osteosarcoma can infrequently show nuclear FOS expression and a small fraction of osteoblastomas seem to arise independent of FOS/FOSB rearrangements. Acid decalcification and tissue preservation are additional factors that can negatively influence immunohistochemical testing and make diagnostic decision-making challenging in individual cases. Particularly aggressive appearing osteoblastomas, also referred to as epithelioid osteoblastomas, and osteoblastoma-like osteosarcoma can be difficult to distinguish, underlining the need for additional markers to support the diagnosis. Methylation and copy number profiling, a technique well established for the classification of brain tumors, might fill this gap. Here, we set out to comprehensively characterize a series of 77 osteoblastomas by immunohistochemistry, fluorescence in-situ hybridization as well as copy number and methylation profiling and compared our findings to histologic mimics. Our results show that osteoblastomas are uniformly characterized by flat copy number profiles that can add certainty in reaching the correct diagnosis. The methylation cluster formed by osteoblastomas, however, so far lacks specificity and can be misleading in individual cases.

Activating mutations in the MAP-kinase pathway define non-ossifying fibroma of bone.

Non-ossifying fibroma (NOF), which occasionally results in pathologic fracture, is considered the most common benign and self-limiting lesion of the growing skeleton. By DNA sequencing we have identified hotspot KRAS, FGFR1 and NF1 mutations in 48 of 59 patients (81.4%) with NOF, at allele frequencies ranging from 0.04 to 0.61. Our findings define NOF as a genetically driven neoplasm caused in most cases by activated MAP-kinase signalling. Interestingly, this driving force either diminishes over time or at least is not sufficient to prevent autonomous regression and resolution. Beyond its contribution to a better understanding of the molecular pathogenesis of NOF, this study adds another benign lesion to the spectrum of KRAS- and MAP-kinase signalling-driven tumours. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Evaluation of the current use of imaging modalities and pathogen detection in children with acute osteomyelitis and septic arthritis.

Diagnostic tools for the management of acute osteomyelitis (OM) and septic arthritis (SA) have improved over the last decade. To investigate the influence and availability of magnetic resonance imaging (MRI) and nucleic acid testing (NAT), a retrospective cohort study was done. Patients admitted with acute OM or SA between 2005 and 2014 were identified using ICD-10 discharge codes. Ninety-six children were identified: OM, n = 45; SA, n = 42; and OM + SA, n = 9. Diagnostic imaging was performed in 100% of OM or OM + SA and 95% of SA patients. MRI was performed in 85% of OM patients, 26% of SA patients and 100% OM + SA patients. In patients with OM or SA, concomitant joint/bone involvement was detected in 24 and 36% of patients, respectively. In 58% of patients, a pathogen was detected (Staphylococcus aureus, Streptococcus pyogenes and Streptococcus pneumoniae being most common). Blood and tissue culture were positive in 41 and 86% for OM patients and in 14 and 41%, respectively, for SA patients. In 42% of patients, no pathogen was identified, of which 40% had no material for blood or tissue culture/NAT taken. CONCLUSION: Optimal use of imaging modalities including MRI and systematic pathogen detection including NAT should be advocated to limit use of broad spectrum antibiotics and treatment duration. What is Known: • Magnetic resonance imaging and sonography have the best sensitivity for detection of acute osteomyelitis and septic arthritis in children. • Systematic use of blood cultures, tissue cultures and nucleic acid testing improves pathogen detection in children with acute osteomyelitis and septic arthritis. What is New: • The added value of imaging modalities other than magnetic resonance and sonography for detection of osteomyelitis and septic arthritis is limited, and their routine use should be questioned. • Despite availability of optimal pathogen detection methods, missed opportunities to improve pathogen detection are frequent.

Tumor-associated FGF-23-induced hypophosphatemic rickets in children: a case report and review of the literature.

BACKGROUND: Tumor-associated fibroblast growth factor 23 (FGF-23)-induced hypophosphatemic rickets is a rare but known pediatric entity first described in 1959. It results from local production of phosphatonins by benign and malignant mesenchymal tumors. CASE-DIAGNOSIS/TREATMENT: We report an 8-year-old boy with tumor-associated hypophosphatemic rickets due to paraneoplastic FGF-23 secretion from a benign mesenchymal pelvic-bone tumor. Excessive FGF-23 production was visualized by immunohistochemistry in the resected tumor. Phosphate wasting stopped immediately after tumor resection. We reviewed 26 reports of pediatric patients with tumor-induced hypophosphatemic rickets; paraneoplastic FGF-23 secretion was documented in only three of them. All tumors developed inside bone, were benign in 21/26 cases, and were localized in femur/tibia (13/26), radius/ulna/humerus (7/26), pelvis (4/26), rib (1/26), and craniofacial (1/26) bones. Mean interval between onset of signs and/or symptoms and diagnosis was 34 months. CONCLUSIONS: In patients with hypophosphatemic rickets acquired beyond infancy, radiologic investigations for bone tumors need to be performed rapidly. In contrast to biochemical screening for increased circulating FGF-23 levels, immunohistochemical confirmation of FGF-23 production in resected tumor tissue can be regarded as being well established.

[Treatment of pediatric bone tumors around the knee]. / Behandlung kniegelenksnaher Knochentumoren im Wachstumsalter.

Primary bone tumors are rare but more frequently seen during childhood and with predilection for the distal femur and proximal tibia. Therapy of benign tumors-if indicated-includes surgical resection in most cases, whereas malignant bone tumors such as osteo- and Ewing's sarcomas are treated with chemotherapy, wide resection and/or radiation therapy (Ewing's sarcoma). The reconstruction of emerging bone defects is significantly influenced by surgeon-related preferences and tumor-associated factors, respectively. Double-barrel vascularized fibula grafts or extracorporeally irradiated autografts in combination with a free fibula transplant are preferred biological reconstruction techniques around the knee joint. In cases in which the knee joint cannot be preserved, reconstruction is performed using tumor endoprostheses, but potentially emerging leg length discrepancies after resection of a potent physis must be taken into account. In considerably young patients, rotationplasty might represent a viable option with promising functional results.

Synovial sarcoma: the misdiagnosed sarcoma.

Synovial sarcoma is a rare and highly malignant soft tissue sarcoma. The inconspicuous and diversity of its early symptoms make it a highly misdiagnosed disease. The management of synovial sarcomas is challenging as they are rare and have a poor prognosis. Early and correct diagnosis and treatment are critical for clinical outcomes. Misdiagnosis or delayed diagnosis can have devastating consequences for the patient. The detection of SS18 gene rearrangement is considered a powerful tool in establishing the diagnosis of synovial sarcomas. Biopsies and testing for gene rearrangements are recommended for all patients in whom SS cannot be excluded. Surgery is the mainstay of treatment for synovial sarcomas. Neoadjuvant/adjuvant radiotherapy is recommended for patients with big tumors (>5 cm) or positive resection margins, and neoadjuvant/adjuvant chemotherapy is recommended for patients with high-risk tumors or advanced diseases. This article reviews synovial sarcomas from the perspectives of clinical and radiological presentation, histological and cytogenetic analysis, differential diagnosis, treatment, and prognosis.

Preventing of nonunion in congenital pseudarthrosis of the tibia cases of Crawford Type I and II through the use of allograft bypass and a brace: Midterm findings.

Background: Congenital pseudarthrosis of the tibia is a limb deformity, which can be distressing for the affected patients and the pediatric orthopedic surgeons involved. We hypothesized that the modified McFarland procedure would avoid fractures and even have a corrective effect on the affected tibia in congenital pseudarthrosis of the tibia patients. Toward this end, we evaluated the midterm results of treating congenital pseudarthrosis of the tibia patients of Crawford Type I and II with allograft bypass combined with long-term bracing. Methods: This study retrospectively evaluated 7 patients with congenital pseudarthrosis of the tibia who were treated with allograft bypass combined with long-term bracing between 2009 and 2018. The median follow-up was 7.0 years (range 3.8-10.0 years). The medical records and radiographs were reviewed for demographic data, clinical characteristics, outcomes, and complications. Results: At the time of the last follow-up, all allografts revealed complete consolidation in the patients' tibiae at both ends. All patients presented no functional restriction of the lower limbs and no amputation or non-union has occurred. Most of the obvious deformities of the tibia diaphysis or ankle joint were corrected. Two complications occurred that required successful revision surgery. Conclusion: In this series of seven congenital pseudarthrosis of the tibia patients, the allograft bypass technique showed satisfactory midterm results and validated our hypothesis. For congenital pseudarthrosis of the tibia patients of Crawford Type I and II, this procedure combined with long-term bracing, which involves the affected leg only, can delay or possibly prevent fractures, decrease tibial malalignment, and preserve leg length. Level of evidence: level IV.

How much is a leg worth following radical tumor resection in bone sarcomas? Literature review.

Bone sarcomas of the lower extremities are rare malignancies occurring mostly amongst adolescents and young adults. Necessarily, the therapy conducted in sarcoma centers is multimodal and multidisciplinary. In certain cases, in a metastasis free situation with adequate therapy, an overall survival rate of 90% can be achieved. Two principal surgical procedures exit for the local control of the malignancy: 1. Limb salvage with biological with/or endoprosthetic reconstruction; and, 2. amputation with restoration of the function with exoprosthesis or endo-exoprosthesis. Currently, limb salvage procedures are performed in up to 95% of cases. In contrast, amputation is performed when the disease has reached an advanced stage or limb salvage has failed. Both of the surgical options have their risks and possible complications. According to the literature, there should be no significant difference between limb salvage and amputation with respect to long-term overall survival, overall quality of life, psycho-socio-economic outcomes, or patient satisfaction. An important advantage of limb salvage is greater everyday functionality. With the expanded indication of limb salvage and great survival rates, the cases of late complications in patients expecting to maintain their own leg continues to increase. In some cases, it requires multiple interventions, ranging from minor up to the most complex revisions, to maintain the functionality of the extremity. Despite the great costs, personal effort, and the possible complications, limb salvage could be a suitable method to achieve functionally beneficial outcomes and patient satisfaction in bone sarcomas of the lower extremities over the long-term even in cases involving complications.

Conservative and Surgical Treatment of Osteochondromas in Children, Particularly with or without Surgical Lengthening of the Ulna.

Prevention of rotatory impairment and radial head dislocation in the forearm is an important aspect when treating children with osteochondromas. Various studies tried to determine the best treatment, describing different surgical techniques. No consensus has been reached yet. This retrospective study compares the treatment outcome of patients with osteochondroma of the radius and ulna after surgical or conservative treatment. Seventeen forearms treated over a period of 20 years were analysed. Outcome parameters were the prospectively collected clinical data and the radiological findings: "relative shortening" of ulna/radius, the "radial articular angle" (RAA) and the "carpal slip" (CS). Our study shows an improvement of the range of motion and cosmetic appearance of the forearm after an operative procedure, with or without bone lengthening. We observed an increase in wrist and elbow mobility with a decrease in pain scores and a confirmed high cosmetic satisfaction in almost 70% of the patients after bone lengthening and up to 85% after simple excision. For patients suffering from functional impairment or pain, an operative approach is beneficial. Multiple and repetitive osteochondroma excisions are recommended during growth to prevent deformity and rotatory motion restriction. Lengthening procedures require a careful indication.

Vascularized Growth Plate Transfer in Paediatric Ulna Non-Union: Operative Technique and Review of the Literature.

Congenital pseudarthrosis of forearm fractures is rare and is strongly associated with neurofibromatosis type 1 (NF1). Our case report illustrates the progression of a non-union of the ulna after minor trauma in a twelve-year-old boy, newly diagnosed with NF1, and presents the technique of microsurgical bone reconstruction, including the growth plate. More than seven years after the first operation, follow-up presents a favorable outcome with a pain-free patient and unrestricted function of the forearm after a secondary correction of the remaining radial bowing. This treatment is discussed with a comprehensive review of the current literature on ulnar congenital pseudarthrosis in PubMed and Google Scholar and free fibular growth plate transfer in PubMed and Google Scholar. Nine publications reporting on 20 cases of congenital ulnar non-unions were identified. With this reconstructive option, favorable outcomes were achieved in all cases with the union after primary surgery and complications requiring further surgeries in nine cases. The benefit of vascularized growth plate bone transfer in congenital ulna non-union seems to be significant compared to other therapies such as open reduction internal fixation (ORIF), non-vascularized bone grafts, or one-bone-forearms and beneficial when growth reconstruction is needed. Other techniques might be necessary to improve insufficient long-term results.

Exploring the Potential of Electronic Patient-Reported Outcome Measures to Inform and Assess Care in Sarcoma Centers: A Longitudinal Multicenter Pilot Study.

BACKGROUND: Electronic patient-reported outcome measures (ePROMs) are useful tools to assess care needs of patients diagnosed with cancer and to monitor their symptoms along the illness trajectory. Studies regarding the application of ePROMs by advanced practice nurses (APNs) specialized in sarcoma care and the use of such electronic measures for care planning and assessing quality of care are lacking. OBJECTIVE: To explore the potential of ePROMs in clinical practice for assessing the patient's quality of life, physical functionality, needs, and fear of progression, as well as distress and the quality of care in sarcoma centers. METHODS: A multicenter longitudinal pilot study design was chosen. Three sarcoma centers with and without APN service located in Switzerland were included. The instruments EQ-5D-5L, Pearman Mayo Survey of Needs, the National Comprehensive Cancer Network Distress Thermometer, PA-F12, and Toronto Extremity Salvage Score were used as ePROMs. Data were analyzed descriptively. RESULTS: Overall, 55 patients participated in the pilot study; 33 (60%) received an intervention by an APN, and 22 (40%) did not. Patients in sarcoma centers with APN service reported overall higher scores in quality of life and functional outcome. The number of needs and distress level were lower in sarcoma centers with APN service. No differences were found with respect to patients' fear of progression. CONCLUSIONS: Most of the ePROMs proved to be reasonable in clinical practice. PA-F12 has shown low clinical relevance. IMPLICATIONS FOR PRACTICE: Using ePROMs appears to be reasonable to obtain clinically relevant patient information and to evaluate the quality of care in sarcoma centers.

[Proximal femoral varus osteotomy in Legg-Calve-Perthes disease]. / Proximale Varisationsosteotomie des Femurs beim Morbus Perthes.

OBJECTIVE: The proximal femoral varus osteotomy (FVO) aims to re-centre the femoral head in the acetabular socket after prognostically unfavourable subluxation, e.g. in Legg-Calve-Perthes disease (LCPD). INDICATIONS: No unified indication criteria have been defined yet for containment therapy in LCPD. However, specific radiographic features related to deformity development, age at diagnosis or onset and classifications describing pathomorphological changes in the femoral head related to bone necrosis can support decisionmaking. CONTRAINDICATIONS: Absolute contraindications-a hinge abducted joint; failure of femoral head reduction in the 20° abduction anteroposterior view; total epiphyseal necrosis. Relative contraindication-children < 6 years, in lateral pillar classification group A or Catteral group I and II. SURGICAL TECHNIQUE: Lateral approach to the proximal femur. Insertion of the first K­wire to mark the anteversion of the femoral neck. Additional K­wires are placed parallel to the first via the positioner aiming block. Lokalise the optimal postion for the osteotomy. Insertion of additional K­wires in the distal fragment an facilitate manipulation and serve as reference for derotation. After osteotomy proximal fixation of the plate with locking screws replacing the K-wires. Insertion of a cortical screw into the middle hole to achieve optimal interfragmentary compression. Remaining locking screws are inserted and cortical screw replaced by a locking screw. POSTOPERATIVE MANAGEMENT: Mobilization with heel-touch weight-bearing on crutches for 6 weeks. Increased weightbearing after radiographic follow-up as soon as sufficient bone union is present. Implant removal after 9-12 months. Return to sports after 3 months. RESULTS: The FVO has been used in the surgical treatment of severe LCPD for nearly 60 years and is established worldwide. Growing knowledge and consecutive optimization of the surgery indication together with the new implants contribute to improving clinical and radiological outcomes and reducing intraoperative and postoperative complications.

Personalized 3D-printed guide in malignant bone tumor resection and following reconstruction - 17 cases in pelvic and extremities.

INTRODUCTION: Customized accurate tumor resection and individualized reconstruction is a challenging in treatment of malignant bone tumor. Three-dimensional (3D)-printing technique is now widely used in the resection and following reconstruction of malignant bone tumor, which included but not limited to tumor model, osteotomy guide and customized implant. METHODS: We retrospectively reviewed 17 patients, who underwent limb salvage surgery by using 3D-printed guide at a single center between August 2014 and October 2019. The median duration of follow-up was 26.5 months. Osteosarcoma (41.2%) were the predominant diagnoses. The functional outcomes were assessed by Musculoskeletal Tumor Society (MSTS) functional score. We also analyzed survival status, intraoperative data (blood loss, operation time and resection length), reconstruction method, margin outcomes and complications. RESULTS: We totally performed 93 guided osteotomies on affected bone and allograft bone in 17 patients. Reconstruction in 12 cases was performed with biological technique: allograft combined with autograft was used in 7 cases. 11 of 12 (91.7%) cases showed a good bone healing in both allograft and autograft. 1 of 12 (8.3%) cases had allograft necrosis. Additional intra-operative extracorporeal radiation was performed in 3 pelvic cases for reconstruction. 63 of 64 (98%) osteotomies achieved wide resection and negative margin. All the cases had successful limb salvage result without amputation. At the latest follow up, the mean MSTS Score was 24 (range: 13-30), 12 patients alive with no evidence of disease, 1 patient alive with disease, 5 patients had died of disease and 5 years overall survival is 73.3%. The most common complications are wound healing disorder in 4 cases (23.5%) and infection in 3 cases (17.6%). CONCLUSION: The 3D-printed resection guide was easy to use and showed promise in the field of orthopedic oncology. It can not only used in primary malignant bone tumor personalized resection but also in shaping structural bone allograft in biological reconstruction, which can achieve a safety surgical margin and individualized resection at the same time.

Vascularized and Non-vascularized Fibula Grafts in Tumour Reconstruction: Single Centre Experience With Mid to Long-term Results.

BACKGROUND/AIM: Vascularized (VFG) and non-vascularized fibula grafts (NVFG) are used in reconstruction of bone defects after tumour resection. This study compared both autografts and their results, risk factors, and complications. PATIENTS AND METHODS: Tumour resection and reconstruction by using VFG (n=17) and NVFG (n=36) were performed in 53 patients at our institute (range=3-65 years of age, mean: 21.2 ± 13.2 years) of which 24 were female. Malignant tumours were diagnosed in 26 patients (VFG=16 patients-94%). The mean follow-up was 14.9 years (range=1.5-43 years). Factors like consolidation, functional and oncologic outcomes, and complications were analysed. RESULTS: In total, 75 struts of fibula were obtained. The mean length of the fibula was 16.3 cm (16 in NVFG and 16.5 in VFG). The mean union time was 13 months (6 to 25 months) overall. Hypertrophy was found in 65 of 75 grafts (86.7%) and consolidation was found in 69 (92%). Hypertrophy was similar in VFG (85.3%) and NVFG (87.1%). Complication rate in VFG was 41% and in NVFG 25%. Fractures were found in 7 (13%), infections in 4 (7.5%), and non-union in 5 (9.4%) patients. Chemotherapy was the only negative prognostic factor for union time (p=0.021). CONCLUSION: Both VFG and NVFG are used with successful results in the reconstruction of segmental bone tumour defects. With lower complication rates, NVFG showed comparable results to VFG but is limited in indication by size for greater defects, and malignant tumours. Chemotherapy is an adverse factor leading to prolonged union time in both techniques.

The "true" acetabular anteversion angle (AV angle): 2D CT versus 3D model.

INTRODUCTION: Different factors can lead to inconsistencies in measurement for the acetabular version using 2D axial CT-cuts. We have defined a "true" anteversion angle (AV angle) in the physiological position of the pelvis in 3D with the largest European population measured to our knowledge. MATERIAL AND METHODS: We analyzed 258 hemipelvises and created 3D models. We compared the results of our AV angle 3D method with the cross-sectional cuts of the same acetabula. We included factors like side, sex, body mass index, and patient positioning. RESULTS: Overall, the mean (SD) AV angle was 16.1 (5.9)° as measured with the 3D method and 22.0 (6.0)° as measured with the 2D method (p < 0.0001). Measured with both the 3D and the 2D method, the AV angle was significantly larger in female than in male individuals (p < 0.0001). In the 2D method, the AV angle estimation was influenced by the pelvic tilt. CONCLUSION: We propose a more accurate method for the measurement of the AV angle of the acetabulum in a 3D model that is not influenced by patient positioning or pelvic tilt. We provide a computational model that will facilitate operative decisions and improve preoperative planning. We confirm that 3D measurement should be the gold standard in measuring the acetabular anteversion.

FGF-23 transmitted tumor - induced hypophosphatemic osteomalacia: A rare case of a young woman with recurrent fractures and review of the literature.

We present a case of tumor-induced osteomalacia (TIO) in a young woman of 22 years. The fibroblast growth factor 23 transmitting tumor in her left foot remained undetected for several years. She suffered several fractures including insufficiency fractures of both femoral necks requiring bilateral proximal femoral nailing. After phosphaturia was diagnosed any known genetic etiology was excluded. Even advanced imaging modalities were unable to detect the clinically silent tumor until an 68Ga-DOTA-TOC-PET/CT-scan revealed a mass with paraneoplastic activity in the left foot. Complete resection of the tumor proved to cure her condition after 9 years of uncertainty and suffering. Serum phosphate levels returned to normal within days. After presentation of the case report, the current literature on published cases of TIO between 1956 and 2021 is summarized to emphasize the importance of an accurate and early diagnosis. Our case report aims to illustrate that a long latency period of diagnosis may be avoided utilizing the latest imaging techniques to spare affected patients from long treatment of symptoms instead of finding the underlying cause.

3D video-based deformation measurement of the pelvis bone under dynamic cyclic loading.

BACKGROUND: Dynamic three-dimensional (3D) deformation of the pelvic bones is a crucial factor in the successful design and longevity of complex orthopaedic oncological implants. The current solutions are often not very promising for the patient; thus it would be interesting to measure the dynamic 3D-deformation of the whole pelvic bone in order to get a more realistic dataset for a better implant design. Therefore we hypothesis if it would be possible to combine a material testing machine with a 3D video motion capturing system, used in clinical gait analysis, to measure the sub millimetre deformation of a whole pelvis specimen. METHOD: A pelvis specimen was placed in a standing position on a material testing machine. Passive reflective markers, traceable by the 3D video motion capturing system, were fixed to the bony surface of the pelvis specimen. While applying a dynamic sinusoidal load the 3D-movement of the markers was recorded by the cameras and afterwards the 3D-deformation of the pelvis specimen was computed. The accuracy of the 3D-movement of the markers was verified with 3D-displacement curve with a step function using a manual driven 3D micro-motion-stage. RESULTS: The resulting accuracy of the measurement system depended on the number of cameras tracking a marker. The noise level for a marker seen by two cameras was during the stationary phase of the calibration procedure ± 0.036 mm, and ± 0.022 mm if tracked by 6 cameras. The detectable 3D-movement performed by the 3D-micro-motion-stage was smaller than the noise level of the 3D-video motion capturing system. Therefore the limiting factor of the setup was the noise level, which resulted in a measurement accuracy for the dynamic test setup of ± 0.036 mm. CONCLUSION: This 3D test setup opens new possibilities in dynamic testing of wide range materials, like anatomical specimens, biomaterials, and its combinations. The resulting 3D-deformation dataset can be used for a better estimation of material characteristics of the underlying structures. This is an important factor in a reliable biomechanical modelling and simulation as well as in a successful design of complex implants.

Intramedullary leg lengthening with a motorized nail.

BACKGROUND AND PURPOSE: In the last decade, intramedullary limb lengthening has become a viable alternative to traditional external systems. We retrospectively analyzed the use of an intramedullary motorized nail (Fitbone) in a consecutive series of 32 patients. PATIENTS AND METHODS: During the period September 2006 to December 2008, 32 consecutive patients with a median age of 17 (IQR: 15-19) years were treated with a fully implantable, motorized intramedullary lengthening device (Fitbone). The median leg length discrepancy was 35 (IQR: 30-44) mm at the femur (n = 21) and 28 (IQR: 25-30) mm at the tibia (n = 11). RESULTS: Leg lengthening was successful in 30 of 32 cases, with no residual relevant discrepancy (± 5 mm). No intraoperative complications were observed. The consolidation index was significantly different (p = 0.04) between femoral lengthening (mean 35 days/cm) and tibial lengthening (mean 48 days/cm) but did not depend on age older/younger than 16 or previous operations at the affected site. 3 problems, 3 obstacles, and 4 complications (3 minor, 1 major) were encountered in 8 patients, 5 of which were implant-associated. INTERPRETATION: This technique even allows correction in patients with multiplanar deformities. Compared to external devices, intramedullary systems provide comfort and reduce complication rates, give improved cosmetic results, and lead to fast rehabilitation since percutaneous, transmuscular fixation is prevented. This results in reasonable overall treatment costs despite the relatively high costs of implants.

Primary malignant bone tumours of spine and pelvis in children.

PURPOSE: Axial malignant bone tumours are rare in children and adolescents, and their prognosis is still relatively poor due to non-specific symptoms, such as back or groin pain, which may result in late hospital presentation. Therefore, it is very important to raise awareness regarding this pathology. METHODS: We performed a narrative review, including scientific publications published in English. We searched Medline and Google Scholar databases for information on the incidence and prognosis of axial malignant bone tumours in children and adolescents (< 18 years). Outcomes of different surgical management strategies and reconstruction options were assessed. RESULTS: The incidence of primary malignant bone tumours before the age of 18 years is approximately five per one million population; around 25% of these tumours are located in the axial skeleton. With a five-year survival rate of 50%, tumours in an axial location (chest cage, spine, pelvis) are associated with a poorer prognosis than tumours in more peripheral locations. En bloc excision with clear margins has been shown to improve local control and overall survival, even though obtaining adequate surgical margins is difficult due to the close location of large neurovascular structures and other major organs. Spinal reconstruction options include instrumented fusion with allograft or expandable cage. Pelvic reconstruction is needed in internal hemipelvectomy, and the options include biological, endoprosthetic reconstructions, hip transposition, arthrodesis or creation of pseudoarthrosis and lumbopelvic instrumentation. CONCLUSION: Early diagnosis, a timely adequate multidisciplinary management, appropriate en bloc excision, and reconstruction improve survival and quality of life in these patients. LEVEL OF EVIDENCE: V.