[Biomechanical modeling and the relevance for total hip arthroplasty]. / Biomechanische Modellierung und ihre Bedeutung für die Hüftendoprothetik.

BACKGROUND: Providing the hip with an endoprosthesis is one of the most common orthopedic interventions in Germany. The long-term success of such a procedure depends on the consideration of the loads due to muscle and joint forces in the planning and operative care. Patient-specific information of forces acting in vivo is not available to the surgeon in clinical routine today. This is where biomechanical modeling comes in. PROCEDURES: A field of activity of biomechanical modeling is the development of methods and procedures for the precise analysis and simulation of endoprosthetic supplies. The aim was to show the possibilities of biomechanical modeling in total hip arthroplasty by means of two examples (sensitivity analysis and pre-/postoperative comparison of intervention outcome). RESULTS: The results of the sensitivity analysis showed that by modeling the position of an optimal reconstruction of the hip rotational center can be found and the forces acting on the hip joint minimized. In the case of the pre-/postoperative comparison, it can be analyzed whether there has been a decrease or increase of load postoperatively, respectively, or whether the conditions are considered to be approximately equal to the preoperative situation. In the future, biomechanical modeling will be able to significantly improve long-term function by reducing wear and optimizing muscular function of the joint. Therefore, the routine use of validated musculoskeletal analysis in the context of standardized preoperative planning and intraoperative navigation-based implementation should be considered. Thus, validated analyses of musculoskeletal loads not only contribute to the extension of basic knowledge but also to the optimization of endoprosthetic care through their integration into the clinical workflow.

[Resection margins in soft tissue sarcomas]. / Resektionsgrenzen bei Weichteilsarkomen.

BACKGROUND: Soft tissue sarcomas (STS) are a rare and heterogeneous group of malignant tumors that arise from the mesenchymal tissue. STS can form anywhere in the human body, with the extremities being preferred sites of predilection. TREATMENT: A fundamental pillar of treatment is the surgical resection of soft tissue sarcomas. The goal is always an R0 resection with a safety margin. There is no consensus in the literature about the desired tumor-free resection margin. The decisive factors for these resection margins are histopathology, presence of anatomical barriers (capsule, tendon, fascia, cartilage, periosteum) and possibilities of (neo-) adjuvant therapy. DISCUSSION: References in the literature support the role of resection margins as a predictor of local recurrence. Regarding the role of resection margins in overall survival, available data is divergent. There are known prognostic factors that influence overall survival, such as histological subtype, tumor size, tumor grading, and presence of metastases. So far, several studies have attempted to quantify the margins of resection, but no consensus has been reached, and debates are ongoing. When analyzing all the results of the data in the literature, it seems appropriate to aim for a negative resection margin >1 mm including an anatomical border structure, if possible.

[Differentiated treatment strategies for bone metastases of the extremities]. / Differenzierte Therapiestrategien bei Knochenmetastasen der Extremitäten.

BACKGROUND: Bone metastases are the most common malignant bone tumours and most commonly occur in the spine, pelvis, proximal femur and proximal humerus. Prostate and breast cancer most often metastasize to the bone. DIAGNOSTICS: In patients with a history of tumours and local unspecific pain in the back and extremities, further diagnostic examinations should be performed. For the initial diagnosis a conventional radiograph of the whole bone in two planes is sufficient. For further diagnostics, the imaging may be supplemented with CT, MRI, scintigraphy and a PET-CT (PET-MRI) if the findings are not inconspicuous on the x­ray. An indication for biopsy exists if the tumor cannot be classified, especially in solitary findings with or without previous tumor anamnesis. THERAPY: Surgical indications for bone metastases are a pathological fracture, an impending fracture, a solitary late metastasis, radiation-resistant osteolysis and therapy-resistant pain. In solitary metastases, the prognosis for patients can be significantly improved by a wide (R0 resection) depending on the primary tumour. For multiple metastases the restoration of mobility and improvement of the quality of life are in the foreground. Depending on the life expectancy and other factors, such as the location of the metastases osteosynthesis, implantations of dual head prothesis, total joint arthroplasty and tumor endoprostheses can be performed.

[Revision total hip arthroplasty : Significance of instability, impingement, offset and gluteal insufficiency]. / Revisionsendoprothetik der Hüfte : Bedeutung von Instabilität, Impingement, Offset und Glutealinsuffizienz.

BACKGROUND: Instability is a common cause of failure in primary and, especially, revision total hip arthroplasty. The reasons for instability include implant malpositioning, impingement, inadequate offset reconstruction, and gluteal insufficiency. Impingement following THA and revision THA is divided into prosthetic and bony impingement, and in addition to instability also causes pain in the area of the hip joint. Offset reconstruction during revision THA is of particular biomechanical importance, since insufficient reconstruction leads not only to instability and pain but also to dislocation. Abductor deficiency often occurs after revision THA and leads to a change in gait pattern, instability and pain. AIM: Current diagnostic and treatment procedures for instability, impingement, insufficient offset reconstruction and abductor deficiency after THA and revision THA are summarized. RESULTS AND DISCUSSION: Diagnosis of an instable THA and painful THA includes patient history, physical examination and medical imaging. Thus, in almost all cases, the cause can be determined and treated. Dislocation after primary THA in the early postoperative period can often be treated conservatively if accurate component placement is observed, while a late-onset and recurrent dislocation after primary and revision THA usually needs surgical procedures. To avoid bony and prosthetic THA impingement intraoperative control is absolutely necessary. If possible, the offset reconstruction is based on the condition of the native hip joint and can be achieved by using modular prostheses, neck adapters and different head lengths. Abductor deficiency also occurs frequently after revision THA and can be treated surgically if severe clinical symptoms and fatty degeneration of the abductors have been diagnosed.

Non-invasive T1ρ mapping of the human cartilage response to loading and unloading.

OBJECTIVE: To define the physiological response to sequential loading and unloading in histologically intact human articular cartilage using serial T1ρ mapping, as T1ρ is considered to indicate the tissue's macromolecular content. METHOD: 18 macroscopically intact cartilage-bone samples were obtained from the central lateral femoral condyles of 18 patients undergoing total knee replacement. Serial T1ρ mapping was performed on a clinical 3.0-T MRI system using a modified prostate coil. Spin-lock multiple gradient-echo sequences prior to, during and after standardized indentation loading (displacement controlled, strain 20%) were used to obtain seven serial T1ρ maps: unloaded (δ0), quasi-statically loaded (indentation1-indentation3) and under subsequent relaxation (relaxation1-relaxation3). After manual segmentation, zonal and regional regions-of-interest were defined. ROI-specific relative changes were calculated and statistically assessed using paired t-tests. Histological (Mankin classification) and biomechanical (unconfined compression) evaluations served as references. RESULTS: All samples were histologically and biomechanically grossly intact (Mankin sum: 1.8 ± 1.2; Young's Modulus: 0.7 ± 0.4 MPa). Upon loading, T1ρ consistently increased throughout the entire sample thickness, primarily subpistonally (indentation1 [M ± SD]: 9.5 ± 7.8% [sub-pistonal area, SPA] vs 4.2 ± 5.8% [peri-pistonal area, PPA]; P < 0.001). T1ρ further increased with ongoing loading (indentation3: 14.1 ± 8.1 [SPA] vs 7.7 ± 5.9% [PPA]; P < 0.001). Even upon unloading (i.e., relaxation), T1ρ persistently increased in time. CONCLUSION: Serial T1ρ-mapping reveals distinct and complex zonal and regional changes in articular cartilage as a function of loading and unloading. Thereby, longitudinal adaptive processes in hyaline cartilage become evident, which may be used for the tissue's non-invasive functional characterization by T1ρ.

[Total hip replacement in avascular femoral head necrosis]. / Endoprothetik bei aseptischer Femurkopfnekrose.

BACKGROUND: Avascular necrosis of the femoral head is a progressive perfusion disorder of the hip joint. Progress in avascular necrosis causes structural damage to the affected joint, often requiring total hip replacement. AIM: This article is intended to give the reader an overview of the current literature on total hip replacement of patients with an avascular necrosis of the femoral head. RESULTS: Before 1990, patients with avascular necrosis of the femoral head had significantly higher revision rates after total hip replacement. Recent studies, however, showed no significant differences in clinical outcomes after total hip replacement in femoral head necrosis and primary osteoarthritis. Despite the young age of the patients, good long-term clinical results can be expected even in patients with an avascular necrosis of the femoral head after total hip replacement.

[Perthes disease-diagnosis, classification and treatment based on Aachen-Dortmund treatment algorithm]. / M. Perthes ­ Diagnostik, Klassifikation und Therapie anhand des Aachen-Dortmunder Therapiealgorithmus.

Legg-Calvé-Perthes disease is a multifactorial idiopathic necrosis of the hip that typically occurs in childhood between the ages of 3 and 12. Treatment adapted to the stadium of the disease and to the clinical findings is medical art. The treatment is focused on the preservation or recovery of the arthrogenic containment of the femoral head. Multiple treatment options are available. The indications for treatment can be derived from clinical and radiological pathology. Structuring of the therapy options is the aim of this publication. For this purpose, a clear and concise overview of relevant clinical findings and useful radiographic classifications as well as reasonable therapy is presented.

[Chondral and osteochondral defects : Representation by imaging methods]. / Chondrale und osteochondrale Defekte : Darstellung mittels bildgebender Verfahren.

Morphological imaging of cartilage at high resolution allows the differentiation of chondral and osteochondral lesions. Nowadays, magnetic resonance imaging is the principal diagnostic tool in the assessment of cartilage structure and composition. Conventional radiography, computed tomography, ultrasound or optical coherence tomography are adjunct diagnostic modalities in the assessment of cartilage pathologies. The present article discusses the up-to-date diagnostic practice of cartilage imaging in terms of its scientific basis and current clinical status, requirements, techniques and image interpretation. Innovations in the field such as functional MRI are discussed as well due to their mid- to long-term clinical perspective.

[Current overview of cartilage regeneration procedures]. / Aktuelle Übersicht knorpelregenerativer Verfahren.

BACKGROUND: Cartilage is an avascular, alymphatic and non-innervated tissue with limited intrinsic repair potential. The high prevalence of cartilage defects and their tremendous clinical importance are a challenge for all treating physicians. AIM: This article provides the reader with an overview about current cartilage treatment options and their clinical outcome. METHODS: Microfracture is still considered the gold standard in the treatment of small cartilage lesions. Small osteochondral defects can be effectively treated with the autologous osteochondral transplantation system. Larger cartilage defects are successfully treated by autologous membrane-induced chondrogenesis (AMIC) or by membrane-assisted autologous chondrocyte implantation (MACI). CONCLUSION: Despite limitations of current cartilage repair strategies, such procedures can result in short- and mid-term clinical improvement of the patients. Further developments and clinical studies are necessary to improve the long-term outcome following cartilage repair.

S3-Guideline non-traumatic adult femoral head necrosis.

INTRODUCTION: The treatment of adult non-traumatic avascular necrosis of the femoral head (AVN; N-ANFH) within an estimated incidence of 5000-7000 cases per annum in Germany remains a challenge. Risk factors include steroids, alcohol abuse, chemotherapy and immunosuppressive medication, but a genetic predisposition has been suggested. Early diagnosis of this often bilateral disease process is essential for successful conservative or joint preserving surgical management. In this review, we present the update German consensus S3 guideline "diagnosis and management for N-ANFH" as a concise summary. MATERIALS AND METHODS: This systematic review is based on the published literature from January 1, 1970 to April 31, 2013 (German and English language). Inclusion criteria were systematic reviews, meta-analyses and relevant peer review publications. We identified a total of 3715 related publications, of which 422 were suitable according to the SIGN criteria, but only 159 fulfilled our inclusion criteria. RESULTS AND CONCLUSIONS: Clinical suspicion of N-ANFH mandates radiographic evaluation. If radiographs are normal MRI scans are recommended, which should be evaluated according to the ARCO-classification. Differential diagnoses include transient osteoporosis, bone bruise, insufficiency fracture and destructive arthropathy. Untreated, subchondral fractures commonly occur within 2 years, during which the risk for contralateral involvement is high-thereafter unlikely. Conservative management with Ilomedin and Alendronat can be tried, but other pharmacological or physical treatments are inappropriate. No specific joint preserving procedure can be recommended, but core decompression should be considered in early stages if necrosis is <30 %. In ARCO stages IIIc or IV total hip arthroplasty (THA) should be contemplated, which offers similar outcome compared to osteoarthritis. Young age is the main risk factor for higher revision rates after THA for N-ANFH.

[Salter innominate osteotomy : Indications, surgical technique, results]. / Innominatumosteotomie nach Salter : Indikationen, Operationstechnik, Ergebnisse.

The prevalence of congenital hip dysplasia in Germany is 2-4 % and that of hip dislocation is 0.5-1 %. If early therapy is not successful or the hip dysplasia or dislocation is diagnosed too late (children of over 1 year of age) surgical treatment is indicated to increase the femoral coverage. The innominate osteotomy, published by Robert B. Salter 1961, is a worldwide established technique to improve the lateral and ventral coverage of the femoral head in primary or secondary hip dysplasia or dislocation. In this paper we discuss Salter's technique and present indications, the perioperative procedure, operative modifications and operative extensions and demonstrate the anatomical requirements, postoperative biomechanical changes and long-term results.

[Anterior knee pain after total knee arthroplasty : Causes, diagnosis and treatment]. / Vorderer Knieschmerz nach Knie­TEP-Implantation : Ursachen, Diagnostik und Therapie.

BACKGROUND: Anterior knee pain is one of the most common complications after total knee arthroplasty. An incidence of up to 30 % has been reported in peer-reviewed studies. TARGET: The purpose of this study was to systematically review the literature and to identify determinants that have been analyzed with regard to anterior knee pain. CAUSES: Patient- and knee-specific characteristics, prosthetic designs and operative techniques are addressed as well as functional and neurologic determinants. Instability, increased contact pressure in the patellofemoral joint and patella maltracking due to malrotation of components, offset errors, ligament insufficiencies or patella baja are mechanical reasons for anterior knee pain. Functional causes include pathologic gait patterns, quadriceps imbalance and dynamic valgus. They have to be differentiated from infectious and inflammatory causes as well as soft tissue impingement, arthrofibrosis and neurologic diseases. TREATMENT: A differentiated treatment algorithm is recommended. Often conservative treatment options exist, however, particularly with most mechanical causes revision surgery is necessary.

[Hip arthroplasty after corrective osteotomies : Pelvis and proximal femur]. / Hüftendoprothetik nach korrigierenden Osteotomien : Becken und proximales Femur.

BACKGROUND: Pelvic and femoral osteotomies are frequently performed in patients with hip dysplasia. The aim of these surgeries are optimal biomechanical conditions of the hip joint thereby avoiding the occurrence of hip osteoarthritis or the delay of initial hip osteoarthritis progression. THERAPY: Nevertheless even with good biomechanical conditions of the hip joint, progression of hip osteoarthritis can be recognized postoperatively. A total hip arthroplasty is indicated even more after a time period with conservative treatment. In preparation for the operation, a detailed documentation of the initial clinical situation, appropriate imaging, implant selection and preoperative planning are mandatory. In addition, a biomechanical model representing the desired pre- and postoperative situation can be included in the preoperative planning. According to the previous osteotomy, the size and shape of the acetabulum after the osteotomy and the current pivot centre of the hip joint should be considered. Depending on these observations the acetabular cup can be directly inserted into the bone stock of the acetabulum or an acetabular plasty is necessary before implantation of the acetabular cup. With respect to the previous osteotomy of the femur, it needs to be clarified wether hardware removal will be necessary before total hip replacement; moreover, the anatomy of the proximal femur is critical. In addition, if necessary, a re-osteotomy of the femur is required to enable a hip stem implantation. CONCLUSION: Cementless total hip replacement should be preferred due to the younger patient age. The load of the hip replacement depends on the osseous anchoring and primary stability of the acetabular and femoral component.

[Adolescent scoliosis : From deformity to treatment]. / Skoliose im Wachstumsalter : Von der Deformität zur Therapie.

Scoliosis affects up to 6 % of the population. The resulting spine deformity, the increasing risk of back pain, cosmetic aspects, pulmonary disorders if the Cobb angle is > 80°, and the progress of the deformity to > 50° after the end of growth indicate non-operative or operative therapy. In daily clinical practice, the classifications of scoliosis allow the therapy to be adapted. Classifications consider deformity, topography of the scoliosis, and the age at diagnosis. This publication gives an overview of the relevant and most common classifications in the treatment of adolescent scoliosis. For evaluation, the deformity measurement on the coronary radiographic projection of the total spine (Cobb angle) is relevant to therapy. The classification of topography, form, and the sagittal profile of the deformity of the spine are useful for preoperative planning of the fusion level. Classifications that take into account the age at the time of the diagnosis of scoliosis differentiate among early onset scoliosis (younger than 10 years of age), adolescent scoliosis (up to the end of growth), and adult scoliosis. Early onset scoliosis is subdivided by age and etiology. Therapy is derived from the classification of clinical and radiological findings. Classifications that take into account clinical and radiological parameters are essential components of modern scoliosis therapy.

[Radiation-free diagnosis of scoliosis : An overview of the surface and spine topography]. / Strahlenfreie Diagnostik bei Skoliosen : Ein Überblick über die Oberflächen- und Wirbelsäulentopographie.

BACKGROUND: Scoliosis is a complex three-dimensional deformity of the spine, which usually occurs during childhood and adolescence. Up to now, whole spine X-rays have been the therapeutic gold standard in the diagnosis and follow-up of scoliosis. AIM: This review gives a brief overview of the history, technical background and possible fields of use for video-rasterstereography METHODS: Alternative measurement systems have been developed over the past few years for the treatment of scoliosis, because of the risk of radiation exposure of X-rays. The rasterstereographic system Formetric (Diers International GmbH, Schlagenbad) allows a radiation-free, three-dimensional analysis of the back surface and the spine. OUTLOOK: Even dynamic measurements can now be conducted with this rasterstereographic system, which will help to further understand and analyze the human spine.

[Multidisciplinary Rehabilitation and Fast-track Rehabilitation after Knee Replacement: Faster, Better, Cheaper? A Survey and Systematic Review of Literature]. / Multidisziplinäre Rehabilitation und multimodale Fast-Track-Rehabilitation in der Knieendoprothetik: Schneller, besser, günstiger? Eine Umfrage und systematische Literaturrecherche.

INTRODUCTION: The aim of multidisciplinary rehabilitation after total knee replacement (TKA) is to reduce postoperative complications and costs and enable faster convalescence. The goals of fast-track rehabilitation, as a multidisciplinary concept, are to reduce the length of hospital stay and achieve early functional improvements by optimizing the perioperative setting. METHOD: A literature review was carried out for the years 1960-2013. The search terms were: "rehabilitation", "training", "physiotherapy", "physical therapy", "recovery", "exercise program", "knee surgery", "TKA", "total knee replacement", "arthroplasty", "intensive", "multidisciplinary", "accelerated", "rapid" or "fast track". Only randomized controlled trials and metaanalyses were included. A survey was also performed to assess care as actually offered in orthopaedic rehabilitation clinics in North Rhine-Westphalia. RESULTS: A total of 729 articles were identified of which 11 studies were included. Fast-track rehabilitation can significantly reduce both the duration of hospital stay and costs after TKA. Current studies showed that a better short-/middle-term clinical outcome might be achieved with multidisciplinary rehabilitation. However, a difference in the long-term outcome could not be observed. Our survey shows that most patients are admitted to a rehabilitation clinic in a state of poor general condition as well as decreased mobility and knee range of motion. CONCLUSIONS: Fast-track rehabilitation facilitates a shortened hospital stay as well as cost saving. It probably can be used to optimize the condition of the patient before admission to a rehabilitation facility.

[Fusion in adolescent idiopathic scoliosis : Anterior, posterior or combined? One-stage or two-stage?]. / Korrekturspondylodesen von adoleszenter idiopathischer Skoliose : Ventral, dorsal, ventrodorsal? Einzeitig oder zweizeitig?

Scoliosis is a complex, three-dimensional spinal deformity with various causes. Adolescent idiopathic scoliosis (AIS) is the most common form. Surgical treatment is indicated for curves greater than 45-50° meaured using the Cobb method. We can distinguish among posterior, anterior or combined surgical procedures. Today, the posterior, transpedicular approach has revolutionized scoliosis surgery. This review gives an overview of current surgical options in scoliosis treatment.

[Pathophysiology of traumatic bone marrow edema]. / Pathophysiologie des traumatischen Knochenmarködems.

BACKGROUND: Morphologically, bone marrow edema (BME) is an accumulation of fluid in the bone marrow. The BME is per se non-specific but can be identified at an early stage with magnetic resonance imaging (MRI). The underlying pathomechanism remains unclear. The BME can occur as an individual entity and as an accompanying condition of many diseases. The BME can be divided into three groups, ischemic, reactive and mechanical BME. Mechanical BME occurs after trauma or repetitive strain. Typical histological changes are present and there is no clear boundary between edema and microfracture. Some forms of trauma show BME in typical localizations. Both the trauma and the possible accompanying injuries can be indirectly indicated in this way in cases with an unknown trauma mechanism. CONCLUSION: The BME can be present as an isolated entity or as a comorbidity. For initiation of therapy, a comprehensive medical history and targeted diagnostics are indispensable. In some cases BME is indicative of the trauma mechanism and possible further accompanying injuries.