Purpose Selective androgen (ostarine, OST) and estrogen (raloxifene, RAL) receptor modulators with improved tissue selectivity have been developed as alternatives to hormone replacement therapy. We investigated the combined effects of OST and RAL on muscle tissue in an estrogen-deficient rat model of postmenopausal conditions. Methods Three-month-old Sprague Dawley rats were divided into groups: (1) untreated non-ovariectomized rats (Non-OVX), (2) untreated ovariectomized rats (OVX), (3) OVX rats treated with OST, (4) OVX rats treated with RAL, (5) OVX rats treated with OST and RAL. Both compounds were administered in the diet. The average dose received was 0.6 ± 0.1 mg for OST and 11.1 ± 1.2 mg for RAL per kg body weight/day. After thirteen weeks, rat activity, muscle weight, structure, gene expression, and serum markers were analyzed. Results OST increased muscle weight, capillary ratio, insulin-like growth factor 1 (Igf-1) expression, serum phosphorus, uterine weight. RAL decreased muscle weight, capillary ratio, food intake, serum calcium and increased Igf-1 and Myostatin expression, serum follicle stimulating hormone (FSH). OST + RAL increased muscle nucleus ratio, uterine weight, serum phosphorus, FSH and luteinizing hormone and decreased body and muscle weight, serum calcium. Neither treatment changed muscle fiber size. OVX increased body and muscle weight, decreased uterine weight, serum calcium and magnesium. Conclusion OST had beneficial effects on muscle in OVX rats. Side effects of OST on the uterus and serum electrolytes should be considered before using it for therapeutic purposes. RAL and RAL + OST had less effect on muscle and showed endocrinological side effects on pituitary–gonadal axis.

The aim of this study is to determine the critical time intervals and influencing covariates for in-hospital mortality in geriatric trauma and orthopedic patients. During a period of five years, we retrospectively review patients aged > 60 years who were hospitalized at the Department of Trauma, Orthopedic, and Plastic Surgery. The primary outcome is the mean time to death. Survival analysis is performed using an accelerated failure time model. A total of 5388 patients are included in the analysis. Two-thirds underwent surgery (n = 3497, 65%) and one-third were conservatively treated (n = 1891, 35%). The in-hospital mortality rate is 3.1% (n = 168; surgery, n = 112; conservative, n = 56). The mean time to death is 23.3 days (±18.8) after admission in the surgery group and 11.3 days (±12.5) in the conservative treatment group. The greatest accelerating effect on mortality is found in the intensive care unit (16.52, p < 0.001). We are able to identify a critical time interval for in-hospital mortality between days 11 and 23. The day of death on weekend days/holidays, hospitalization for conservative treatment, and treatment at the intensive care unit significantly increase the risk of in-hospital mortality. Early mobilization and a short hospitalization duration seem to be of major importance in fragile patients.

Inclusion body myositis (IBM) is a chronic, mostly treatment-resistant, inflammatory myopathy with a pathology that centers around specific interactions between inflammation and protein accumulation. The study aimed to identify the inflammasome as a key event in the complex network of pathomechanisms. Regulation of the inflammasome was assessed in a well-established pro-inflammatory cell culture model using human myoblasts and primary human myotubes. By quantitative PCR, western blot and immunocytochemistry, inflammasome markers including NLRP3 were assessed in muscle cells exposed to the cytokines IL-1β and IFN-γ. The data were corroborated by analysis of muscle biopsies from patients with IBM compared to other myositis subtypes. In the cell culture model of IBM, the NLRP3 inflammasome was significantly overexpressed, as evidenced by western blot (p = 0.03) and quantitative PCR (p < 0.01). Target genes that play a role in inflammasome assembly, T-cell migration, and MHC-I expression (p = 0.009) were highly co-upregulated. NLRP3 was significantly overexpressed in muscle biopsies from IBM samples compared to disease controls (p = 0.049), including other inflammatory myopathies. Due to the extraordinary features of the pathogenesis and the pronounced upregulation of NLRP3 in IBM, the inflammasome could serve as a key molecule that drives the inflammatory cascade as well as protein accumulation in the muscle. These data can be useful for future therapeutic developments.

The selective androgen receptor modulator ostarine has been shown to have advantageous effects on skeletal tissue properties, reducing muscle wasting and improving physical function in males. However, data on effects in male osteoporosis remain limited. In this study, the effects of ostarine on osteoporotic bone were evaluated in a rat model of male osteoporosis and compared with those of testosterone treatments. Eight-month-old male Sprague-Dawley rats were either non-orchiectomized to serve as a healthy control (Non-Orx, Group 1) or orchiectomized (Orx, Groups 2–6) and then grouped (n = 15/group): (1) Non-Orx, (2) Orx, (3) Ostarine Therapy, (4) Testosterone Therapy, (5) Ostarine Prophylaxis and (6) Testosterone Prophylaxis. Prophylaxis treatments started directly after orchiectomy and continued for 18 weeks, whereas Therapy treatments were initiated 12 weeks after Orx. Ostarine and Testosterone were applied orally at daily doses of 0.4 and 50 mg/kg body weight, respectively. The lumbar vertebral bodies and femora were analyzed using biomechanical, micro-CT, ashing, and gene expression analyses. Ostarine Prophylaxis showed positive effects in preventing osteoporotic changes in cortical and trabecular bone (femoral trabecular density: 26.01 ± 9.1

The selective androgen receptor modulator ligandrol (LGD-4033 or VK5211) has been shown to improve muscle tissue. In the present study, the effect of ligandrol on bone tissue was investigated in ovariectomized rat model. Three-month-old Sprague Dawley rats were either ovariectomized (OVX, n = 60) or left intact (NON-OVX, n = 15). After 9 weeks, OVX rats were divided into four groups: untreated OVX (n = 15) group and three OVX groups (each of 15 rats) treated with ligandrol orally at doses of 0.03, 0.3, or 3 mg/kg body weight. After five weeks, lumbar vertebral bodies (L), tibiae, and femora were examined using micro-computed tomographical, biomechanical, ashing, and gene expression analyses. In the 3-mg ligandrol group, bone structural properties were improved (trabecular number: 38 ± 8 vs. 35 ± 7 (femur), 26 ± 7 vs. 22 ± 6 (L), 12 ± 5 vs. 6 ± 3 (tibia) and serum phosphorus levels (1.81 ± 0.17 vs.1.41 ± 0.17 mmol/l), uterus (0.43 ± 0.04 vs. 0.11 ± 0.02 g), and heart (1.13 ± 0.11 vs. 1.01 ± 0.08 g) weights were increased compared to the OVX group. Biomechanical parameters were not changed. Low and medium doses did not affect bone tissue and had fewer side effects. Body weight and food intake were not affected by ligandrol; OVX led to an increase in these parameters and worsened all bone parameters. Ligandrol at high dose showed a subtle anabolic effect on structural properties without any improvement in biomechanical properties of osteoporotic bones. Considering side effects of ligandrol at this dose, its further investigation for the therapy of postmenopausal osteoporosis should be reevaluated.

Enobosarm (EN), a selective androgen receptor modulator and raloxifene (RAL), a selective estrogen receptor modulator, have been shown to improve bone tissue in osteoporotic males. The present study evaluated the effects of a combination therapy of EN and RAL on bone properties in orchiectomized rats compared to the respective single treatments. Eight-month-old male Sprague–Dawley rats were either left intact (Non-Orx) or orchiectomized (Orx). The Orx rats were divided into four groups (n = 15 each): 1) Orx, 2) EN treatment (Orx + EN), 3) RAL treatment (Orx + RAL), 4) combined treatment (Orx + EN + RAL). EN and RAL (0.4 mg and 7 mg/kg body weight/day) were applied immediately after Orx with a soy-free pelleted diet for up to 18 weeks. The lumbar spine and femora were examined by micro-CT, biomechanical, histomorphological, ashing, and gene expression analyses. EN exhibited an anabolic effect on bone, improving some of its parameters in Orx rats, but did not affect biomechanical properties. RAL exhibited antiresorptive activity, maintaining the biomechanical and trabecular parameters of Orx rats at the levels of Non-Orx rats. EN + RAL exerted a stronger effect than the single treatments, improving most of the bone parameters. Liver weight increased after all treatments; the kidney, prostate, and levator ani muscle weights increased after EN and EN + RAL treatments. BW was reduced due to a decreased food intake in the Orx + RAL group and due a reduced visceral fat weight in the Orx + EN + RAL group. The EN + RAL treatment appeared to be promising in preventing male osteoporosis, but given the observed side effects on liver, kidney, and prostate weights, it requires further investigation.

Selective androgen and estrogen receptor modulators, ostarine (OST) and raloxifen (RAL), reportedly improve muscle tissue and offer therapeutic approaches to muscle maintenance in the elderly. The present study evaluated the effects of OST and RAL and their combination on musculoskeletal tissue in orchiectomized rats. Eight-month-old Sprague Dawley rats were analyzed. Experiment I: (1) Untreated non-orchiectomized rats (Non-ORX), (2) untreated orchiectomized rats (ORX), (3) ORX rats treated with OST during weeks 0–18 (OST-P), (4) ORX rats treated with OST during weeks 12–18 (OST-T). Experiment II: 1) Non-ORX, (2) ORX, 3) OST-P, (4) ORX rats treated with RAL, during weeks 0–18 (RAL-P), 5) ORX rats treated with OST + RAL, weeks 0–18 (OST + RAL-P). The average daily doses of OST and RAL were 0.4 and 7 mg/kg body weight (BW). Weight, fiber size, and capillarization of muscles, gene expression, serum markers and the lumbar vertebral body were analyzed. OST-P exerted favorable effects on muscle weight, expression of myostatin and insulin growth factor-1, but increased prostate weight. OST-T partially improved muscle parameters, showing less effect on the prostate. RAL-P did not show anabolic effects on muscles but improved body constitution by reducing abdominal area, food intake, and BW. OST + RAL-P had an anabolic impact on muscle, reduced androgenic effect on the prostate, and normalized food intake. OST and RAL improved osteoporotic bone. The OST + RAL treatment appeared to be a promising option in the treatment of androgen-deficient conditions and showed fewer side effects than the respective single treatments.

Introduction Regulating excessive activation of fibroblasts may be a promising target to optimize extracellular matrix deposition and myocardial stiffness. Fibroblast activation protein alpha (FAP) is upregulated in activated fibroblasts after myocardial infarction (MI), and alters fibroblast migration in vitro. We hypothesized that FAP depletion may have a protective effect on left ventricular (LV) remodeling after MI. Materials and methods We used the model of chronic MI in homozygous FAP deficient mice (FAP-KO, n = 51) and wild type mice (WT, n = 55) to analyze wound healing by monocyte and myofibroblast infiltration. Heart function and remodeling was studied by echocardiography, morphometric analyses including capillary density and myocyte size, collagen content and in vivo cell-proliferation. In non-operated healthy mice up to 6 months of age, morphometric analyses and collagen content was assessed (WT n = 10, FAP-KO n = 19). Results Healthy FAP-deficient mice did not show changes in LV structure or differences in collagen content or cardiac morphology. Infarct size, survival and cardiac function were not different between FAP-KO and wildtype mice. FAP-KO animals showed less LV-dilation and a thicker scar, accompanied by a trend towards lower collagen content. Wound healing, assessed by infiltration with inflammatory cells and myofibroblasts were not different between groups. Conclusion We show that genetic ablation of FAP does not impair cardiac wound healing, and attenuates LV dilation after MI in mice. FAP seems dispensable for normal cardiac function and homeostasis.

Einleitung Die Bekämpfung der globalen Osteoporose stellt nach wie vor ein vordringliches Gesundheitsproblem dar. In einer alternden Gesellschaft mit immer mehr Frakturen der Wirbelkörper und des proximalen Femurs wird dringend nach neuen Therapieansätzen gesucht. In früheren Studien konnten wir über die vorteilhafte Wirkung der beiden Lipoxygenase-Inhibitoren Baicalein und Zileuton auf osteoporotischen Knochen in einem postmenopausalen Rattenmodell berichten. Während subkutanes Baicalein vorwiegend zu günstigem kortikalen Knochen führt, verstärkte Zileuton in erster Linie die trabekulären Anteile von Wirbelkörper und Oberschenkel.

Objectives Postmenopausal osteoporosis is mainly related to estrogen deficiency following menopause in women. However, also other factors including chronic hyponatremia can influence bone tissue. Hyponatremia is a common electrolyte disorder in the clinical practice which is not usually treated, though it is associated with increased risk of falls and fragility fractures. In a recent clinical study, we reported a high prevalence of chronic hyponatremia (>15 %) in patients with fragility fractures. The intention of this study was to compare the effects of hyponatremia and estrogen depletion on bone tissue in a rat model.

Objective Investigation of the treatment of femur fractures and the type of femur fracture‐associated complications regarding timing of surgery and length of hospital stay. Methods In this retrospective cohort study, a total of 358 hip fractures were evaluated retrospectively from 1 January 2008 until 31 December 2010 at a level I trauma center in Germany. Inclusion criteria was age >18 years and a proximal femur fracture. Both sexes were evaluated. Mean age was 75.5 years, most patients were female (63.7%). Intervention was the operative treatment of proximal femur fracture. Outcome parameters were time until surgery, complications, reoperations, mortality, and length of hospital stay. Results Among the proximal femur fractures (n = 358), 46.6% were pertrochanteric, 11.2% subtrochanteric, and 42.2% femoral neck fractures. Operation upon hip fractures was managed regularly within 24 hours of injury (73%; mean for femoral neck: 28.3 hrs.; mean for pertrochanteric fractures: 21.4 hrs.; mean for subtrochanteric fractures: 19.5 hrs.). Delayed treatment, as well as implantation of hip total endoprosthesis (TEP), increased the overall length of hospital stay (15.4 vs 17.6 days; 18.1 vs 15.8 days). Accordingly, surgical procedures performed within 24 hours of injury resulted in a shorter hospital residence. Longest delay of operation was measured for hip fractures (28.3 hrs.). In 351 patients, secondary injuries were detected in 94 individuals (26%), with fractures being the most common secondary injury (n = 40). We recorded postoperative complications of nonsurgical and surgical origin, and 33.6% of our patient cohort displayed complications. Complications were distributed among 118 patients. There was no significant difference in complications regarding the time of operation, with most nonsurgical and surgical complications appearing within 24 hours after operation (n = 110 vs n = 31). Nonsurgical complications, such as anemia (n = 49) and electrolyte imbalances (n = 30), were observed more frequently than surgical complications (n = 107 vs n = 34); however, these complications were reduced by delay in surgery (82.0% in 6–24 hrs. vs 74.2% in ≥24 hrs.). Anticoagulant therapy and age did not affect postoperative complications. The hospital mortality of patients was 6.2%. Follow‐up was restrained to ambulatory visits in the clinic. Conclusions Surgical management of hip fractures performed within 24 hours of injury minimizes hospital stay. We did not detect significant differences in the spectrum or number of complications regarding delay of surgery. Surgical complications mainly occur with rapid primary care, and medical complications can be reduced by more intensive preparation of patient and operation procedures.

Bisphosphonate alendronate (ALN), phytoestrogen 8-prenylnaringenin (8-PN) and the whole body vibration exert a favorable effect on osteoporotic bone. However, the impact of these treatments and the combination of pharmacological therapies with biomechanical stimulation on muscle and bone has not yet been explored in detail. The effect of ALN and 8-PN and their combination with the vibration (Vib) on skeletal muscle and bone healing was investigated in ovariectomized (Ovx) rats. Three-month old rats were Ovx (n = 78), or left intact (Non-Ovx; n = 12). Five weeks after Ovx, all rats were treated according to the group assignment (n = 12/13): 1) Non-Ovx; 2) Ovx; 3) Ovx + Vib; 4) Ovx + ALN; 5) Ovx + ALN + Vib; 6): Ovx + 8-PN; 7) Ovx + 8-PN + Vib. Treatments with ALN (0.58 mg/kg BW, in food), 8-PN (1.77 mg/kg BW, daily s.c. injections) and/or with vertical vibration (0.5 mm, 35 Hz, 1 g, 15 min, 2x/day, 5x/week) were conducted for ten weeks. Nine weeks after Ovx, all rats underwent bilateral tibia osteotomy with plate osteosynthesis and were sacrificed six weeks later. Vibration increased fiber size and capillary density in muscle, enlarged callus area and width, and decreased callus density in tibia, and elevated alkaline phosphatase in serum. ALN and ALN + Vib enhanced capillarization and lactate dehydrogenase activity in muscle. In tibia, ALN slowed bone healing, ALN + Vib increased callus width and density, enhanced callus formation rate and expression of osteogenic genes. 8-PN and 8-PN + Vib decreased fiber size and increased capillary density in muscle; callus density and cortical width were reduced in tibia. Vibration worsened 8-PN effect on bone healing decreasing the callus width and area. Our data suggest that Vib, ALN, 8-PN, or 8-PN + Vib do not appear to aid bone healing. ALN + Vib improved bone healing; however application is questionable since single treatments impaired bone healing. Muscle responds to the anti-osteoporosis treatments and should be included in the evaluation of the drugs.

In den letzten Jahren haben klinische Studien zu einer Verbesserung des Verständnisses des Krankheitsbilds der kindlichen Patellaluxation geführt. Diese Erkenntnisse haben jedoch noch keinen flächendeckenden Einzug in die klinische Praxis gehalten. Überprüfung und Darstellung notwendiger diagnostischer und therapeutischer Schritte. Systematische Medline-Recherche zu den Stichworten „patellar instability“ und „patellar dislocation“. Alle Abstracts der Trefferliste (3302 Treffer) wurden überprüft und 147 relevante Artikel im Original ausgewertet. Erkenntnisse aus der Erwachsenenmedizin sind weitgehend übertragbar auf Kinder und Jugendliche. Das Reluxationsrisiko kann auch bei Kindern anhand etablierter Parameter eingeschätzt werden. Es besteht ein zunehmender Trend zur primären operativen Versorgung bei erhöhtem Risiko für eine Reluxation. Fugenschonende Operationsverfahren mit MPFL-Plastik sind sicher und zeigen ein gutes Outcome. Bei hohem Risiko für eine Rezidivluxation sollten Kinder und Jugendliche nach Erstluxation operativ stabilisiert werden. Das erforderliche Operationsverfahren ist anhand des individuellen Risikoprofils zu wählen.

Osteoporosis is often accompanied by sarcopenia. The effect of strontium ranelate (SR) on muscle tissue has not been investigated sufficiently. In this study, the effect of different SR treatments on muscle was studied. Additionally, the lumbar vertebrae were analyzed. Three-month-old female rats were divided into five groups (n = 12): Group 1: untreated (NON-OVX); Group 2: ovariectomized and left untreated (OVX); Group 3: SR after OVX until the study ended (13 weeks, SR prophylaxis and therapy = pr+th); Group 4: OVX and SR for 8 weeks (SR prophylaxis = pr); Group 5: SR for 5 weeks from the 8 week after OVX (SR therapy = SR th). SR was applied in food (630 mg/kg body weight). The size of muscle fibers, capillary density, metabolic enzymes, and mRNA expression were assessed in soleus, gastrocnemius, and longissimus muscles. The vertebral bodies underwent micro-CT, biomechanical, and ashing analyses. In general, SR did not alter the muscle histological parameters. The changes in fiber size and capillary ratio were related to the body weight. Myostatin mRNA was decreased in Sr pr+th; protein expression was not changed. SR th led to increase in mRNA expression of vascular endothelial growth factor (Vegf-B). In lumbar spine, SR pr+th enhanced biomechanical properties, bone mineral density, trabecular area, density, and thickness and cortical density. The reduced calcium/phosphate ratio in the SR pr+th group indicates the replacement of calcium by strontium ions. SR has no adverse effects on muscle tissue and it shows a favorable time-dependent effect on vertebrae. A functional analysis of muscles could verify these findings.

Most models of osteoporotic bone fractures are performed unilaterally (UL). We investigated healing of tibia osteotomy performed either UL or bilaterally (BL) in ovariectomized rats. Behavior of animals and muscle structure were assessed. Three-month-old female Sprague-Dawley rats were ovariectomized (n = 32). After 10 weeks, half the rats underwent UL osteotomy of tibia metaphysis (right limb) with plate osteosynthesis. The other rats were osteotomized BL. Half of the rats in each group received either standard pain treatment with carprofen (5 mg/kg body weight (BW), 1x/day for 2 days) or carprofen and buprenorphine (5 mg/kg BW, 1x/day and 0.03 mg/kg BW, 2x/day for 5 days) after osteotomy. The UL rats started to load the injured limb from day 27 ± 9; BL rats did this from day 4 ± 4 onward. The UL rats more frequently loaded only one hind limb; BL rats more often loaded both hind limbs. Osteotomy was not bridged in 20% of UL rats and in 4% of BL rats. Callus volume and bone volume fraction were lower in UL group. Weight and fiber size of UL-intact limb muscles were enhanced, compared to the osteotomized limb and those in BL group. Most of the other parameters which assess physiology, activity, body posture, head, or coat were not different. The effect of two pain therapies was not significant on any variable studied. Welfare of the animals was acceptable in all rats. In UL rats, bone healing was delayed. The more advanced healing in BL rats suggested a positive effect of earlier loading. In studies on bone healing, it is advisable to perform BL osteotomy.

Selective androgen receptor modulators (SARMs) have shown beneficial effects on muscle wasting, general physical function and bone properties in male mammals. However, data on the effects of SARMs in postmenopausal osteoporotic bone are scarce. We evaluated the effects of the SARM drug ostarine on postmenopausal osteoporotic bone in a rat osteoporosis model. Ovariectomy was performed on 46 of 56 3-month-old female Sprague–Dawley rats. Eight weeks after ovariectomy, ostarine was orally administered daily for 5 weeks in dosages of 0.04 (low, OVX + Ost. 0.04), 0.4 (intermediate, OVX + Ost. 0.4), and 4 mg/kg (high, OVX + Ost. 4) body weight. Another ovariectomized group received no ostarine. Lumbar vertebrae and femora were removed for biomechanical, gene expression, ashing, and computer tomography analyses. Low dose showed no effects. The effects of intermediate and high doses were comparable overall. Improvements were mainly seen in structural properties such as bone mineral density and bone volume density. However, the effects in femora were superior to effects in vertebrae. Ostarine treatment for 5 weeks did not improve significantly biomechanical properties. mRNA expression of the receptor activator of NF-κB ligand decreased after treatment, and uterine weight increased. Serum levels of phosphorus increased following ostarine treatment in intermediate and high-dose groups. Short-term treatment of osteoporotic bone with ostarine leads to improvement of several microstructural bone indices. While we did not observe changes in biomechanics, it is conceivable that longer treatment may also improve biomechanical properties. Further studies are needed to characterize longer time effects and side effects of ostarine in osteoporosis.

Rebalancing of the RANKL/OPG system seems to be an effective treatment strategy in postmenopausal osteoporosis. Here, we evaluate the knockdown of RANKL by in-vivo-delivered siRNA in a rat model of osteoporosis. Virus-like-particles (VLPs) derived from polyoma JC virus were used for delivering RANKL siRNA in ovariectomized (OVX) rats. 48 rats were ovariectomized and treated with either 17β-estradiol (E2), VLPs containing RANKL siRNA (siRANKL), or VLPs containing non-cognate siRNA (siCtrl). All OVX groups were subdivided into the prophylaxis group (PG) and the therapy group (TG). The PG received treatment directly after being OVX for 10 weeks. The TG received treatment 5 weeks after being OVX for 5 weeks. Rats were sacrificed 10 weeks after being OVX. Bone and blood samples were analyzed. E2 and siRANKL showed a significant knockdown of RANKL mRNA. A protein knockdown was observed with E2 and siRANKL in the TG but not in the PG. No distinct improvements in biomechanical and morphological properties of the bones were observed after siRANKL treatment. In the PG, E2 protected the bone structure. We demonstrated successful mRNA and protein knockdown by VLP-mediated RNAi in vivo. Knockdown of membranous RANKL did not result in significant improvements of bone properties in this model of early-stage postmenopausal osteoporosis.

Bone bruise is part of the bone marrow edema and described as the footprint of the mechanism of injury. It is caused by trabecular microfractures, hyperemia, bleedings and necrosis without damage of cortical bone. In general bone bruise is detected by MR-Imaging. Bone bruise is often associated with additional joint and bone injuries, but it can be also detected as single injury. In general bone bruise causes pain, but especially athletes can be painless. Isolated bone bruise should be treated with protected weight-bearing and analgesia. Return to functional sport activities needs in average 3 month. Bone bruise can still be present in MRI 12 month after injury. There is evidence for chondral defects in the corresponding articular cartilage after bone bruise.

ZusammenfassungAtypische Femurfrakturen (AFF) stellen einen Sonderfall in der Alterstraumatologie dar und machen im Hinblick auf die Gesamtzahl der Femurfrakturen nur einen geringen Anteil aus. Im Gegensatz zur klassischen Fraktur des proximalen Femurs sind AFF subtrochantär bzw. im Schaftbereich lokalisiert, entstehen häufig ohne adäquates Unfallereignis und zeigen charakteristische Merkmale im Röntgenbild. In vielen Fällen kommt es zu einem bilateralen Auftreten von AFF. Klinisch besteht oftmals Tage bis Monate vor der Diagnose einer AFF ein Prodromalschmerz im entsprechenden Bein bzw. der Leistengegend. Durch die American Society for Bone and Mineral Research (ASBMR) wurden Haupt- und Nebenkriterien zur Definition einer atypischen Femurfraktur erstellt. Diese sollen die Diagnosestellung erleichtern. Zu den Hauptkriterium zählen u. a. die peri- oder endostale Verdickung der lateralen Kortikalis sowie das Fehlen einer Frakturtrümmerzone. Um eine Fraktur als AFF zu definieren, müssen mindestens 4 der 5 Hauptkriterien erfüllt sein. Es gibt Evidenz für eine Korrelation zwischen AFF und der (Langzeit-)Einnahme von Bisphosphonaten. Atypische Femurfrakturen können jedoch auch ohne Bisphosphonateinnahme auftreten. Ist eine AFF diagnostiziert, sollte die Bisphosphonattherapie pausiert werden. Für die Therapie unterscheidet man zwischen kompletter und inkompletter Fraktur. Komplette AFF werden operativ zumeist mit einer Marknagelosteosynthese stabilisiert. Inkomplette Frakturen können konservativ therapiert werden – es gibt jedoch eine hohe Versagerrate mit Progress in eine komplette Fraktur, sodass bei persistierenden Schmerzen eher die prophylaktische Marknagelosteosynthese empfohlen wird. Der Behandlungsverlauf nach bisphosphonatassoziierten AFF ist häufiger mit perioperativen Komplikationen vergesellschaftet als die Behandlung von „typischen“ Femurfrakturen. Somit ist die Kenntnis der Pathophysiologie und der Therapieoptionen der Schlüssel zur erfolgreichen Behandlung dieser Verletzung.