The "hump" a new arthroscopic phenomenon guiding for reliable therapy of osteochondritis dissecans of variable stability status.

INTRODUCTION: Despite 150 years of research, there are currently no reliable morphological characteristics that can be used to differentiate between stable and unstable juvenile osteochondritis dissecans (JOCD) lesions in the knee joint. Arthroscopic probing is still the gold standard. In arthroscopic evaluation, a previously undescribed pattern of a cartilaginous convex elevation ("hump") was identified as a new feature and potential sign of JOCD in transition to instability. The aim of the study was to evaluate the clinical outcomes after surgical intervention (drilling) on the "hump". MATERIALS AND METHODS: In a retrospective case series of sixteen patients with an arthroscopically detectable "hump", the analysis of clinical function scores (Lysholm, Tegner) and morphological MRI monitoring of radiological healing were performed. The assessment of lesion healing was based on pre- and postoperative MRI examinations. The "hump" was defined as an arthroscopically impressive protrusion of the femoral articular surface with a minimally softened, discolored, but intact cartilage margin that, is not mobile upon in the arthroscopic palpation hook test. The primary therapy of choice was drilling of all "humps". RESULTS: The "hump" could be detected arthroscopically in 16 of 59 JOCD lesions. Specific MRI correlations with the "hump" or arthroscopic unstable lesions could not be detected. Not all "humps" showed signs of MRI-based healing after the drilling, and in some a dissection of the osteochondral flap occurred within the first postoperative year. As a result, secondary refixation became necessary. CONCLUSION: In the present study, the "hump" was identified as an important differential diagnostic arthroscopic feature of an arthroscopically primarily stable JOCD lesion, potentially placing the lesion at risk of secondary loosening over time. Therefore, drilling alone may not be appropriate in the event of arthroscopic "hump" discovery, but additional fixation may be required to achieve the healing of the lesion. LEVEL OF EVIDENCE: III.

[Ligamentous knee injuries in children and adolescents]. / Ligamentäre Kniegelenkverletzungen im Wachstumsalter.

Due to an increase in sporting activities, the number of injuries of the immature knee is continuously increasing. These injuries necessitate a special approach regarding the particular anatomical situation with open growth plates. Three of the most commonly occurring injuries are rupture of the anterior cruciate ligament, patella dislocation and meniscus injuries. The clinical results for conservative treatment of ruptures of the anterior cruciate ligament in the growth phase are inferior to operative treatment. Transepiphyseal reconstruction has been shown to be a safe treatment method and provides good clinical results. Therapy of patella instability in children has shown poor results and new surgical techniques have been introduced to perform an anatomical reconstruction of the medial patellofemoral ligament as well as to improve distal alignment. Isolated injuries to the meniscus are rare and discoid meniscus is a special phenomenon occurring in infancy. Meniscus injuries should be treated with primary sutures rather than resection. A discoid meniscus should be resected with extreme caution and anatomically reconstructed.

Autologous chondrocyte implantation (ACI) for cartilage defects of the knee: A guideline by the working group "Clinical Tissue Regeneration" of the German Society of Orthopaedics and Trauma (DGOU).

BACKGROUND: Autologous chondrocyte implantation (ACI) is an established and well-accepted procedure for the treatment of localised full-thickness cartilage defects of the knee. METHODS: The present review of the working group "Clinical Tissue Regeneration" of the German Society of Orthopaedics and Trauma (DGOU) describes the biology and function of healthy articular cartilage, the present state of knowledge concerning therapeutic consequences of primary cartilage lesions and the suitable indication for ACI. RESULTS: Based on best available scientific evidence, an indication for ACI is given for symptomatic cartilage defects starting from defect sizes of more than three to four square centimetres; in the case of young and active sports patients at 2.5cm(2), while advanced degenerative joint disease needs to be considered as the most important contraindication. CONCLUSION: The present review gives a concise overview on important scientific background and the results of clinical studies and discusses the advantages and disadvantages of ACI. LEVEL OF EVIDENCE: Non-systematic Review.

Biomechanical modelling of impact-related fracture characteristics and injury patterns of the cervical spine associated with riding accidents.

BACKGROUND: Horse-related injuries are manifold and can involve the upper and lower limbs, the trunk, spine or head. Cervical spine injuries are not among the most common injuries. However, they can be fatal and often result in neurological symptoms. This study investigated the influence of the posture of the cervical spine on the ultimate strength and the pattern of vertebrae failure with the aim to provide some guidance for protective clothing design. METHODS: Eighteen human cervical spines, each divided into two specimens (three vertebrae each), were subjected to a simulator test designed to mimic a spinal trauma in different postures of the specimen (neutral, flexion, extension). The stress-to-failure, the deformation at the time of fracture and the fracture patterns assessed based on CT scans were analysed. FINDINGS: Stress-to-failure of the superior specimens was lower for the flexion group compared to the others (P=0.027). The superior specimens demonstrated higher stress-to-failure in comparison to the inferior specimens (P<0.001). Compression in a neutral or flexed position generated mild or moderate fracture patterns. On the contrary, the placement of the spine in extension resulted in severe fractures mostly associated with narrowing of the spinal canal. INTERPRETATION: The results imply that a neutral cervical spine position during an impaction can be beneficial. In this position, the failure loads are high, and even if a vertebral fracture occurs, the generated injury patterns are expected to be mild or moderate.

[Autologous chondrocyte implantation (ACI) for cartilage defects of the knee: a guideline by the working group "Tissue Regeneration" of the German Society of Orthopaedic Surgery and Traumatology (DGOU)]. / Stellenwert der autologen Chondrozytentransplantation (ACT) in der Behandlung von Knorpelschäden des Kniegelenks - Empfehlungen der AG Klinische Geweberegeneration der DGOU.

Autologous chondrocyte transplantation/implantation (ACT/ACI) is an established and recognised procedure for the treatment of localised full-thickness cartilage defects of the knee. The present review of the working group "Clinical Tissue Regeneration" of the German Society of Orthopaedics and Traumatology (DGOU) describes the biology and function of healthy articular cartilage, the present state of knowledge concerning potential consequences of primary cartilage lesions and the suitable indication for ACI. Based on current evidence, an indication for ACI is given for symptomatic cartilage defects starting from defect sizes of more than 3-4 cm2; in the case of young and active sports patients at 2.5 cm2. Advanced degenerative joint disease is the single most important contraindication. The review gives a concise overview on important scientific background, the results of clinical studies and discusses advantages and disadvantages of ACI.

[The question of safety in horse-riding sports]. / Zur Frage der Sicherheit im Reitsport.

INTRODUCTION: To reduce the number of equine-related injuries, knowledge about causes of accidents is of great importance. In the present study the causes of equine-related accidents were evaluated by a questionnaire survey. Based on our results options for prevention of equine-related accidents were formulated. MATERIAL AND METHODS: The working-group "safer riding, Hamburg" and the "German riding association (FN)" created a questionnaire to evaluate causes of equine-related accidents. This questionnaire was published in the print media "Cavallo" and "St. Georg" as well as on the online portal www.hamburger-ag-reitersicherheit.de. The questionnaire was intended for all equestrians who had suffered a horse-riding accident in the past. RESULTS: 371 female and 18 male equestrians returned a completed questionnaire. At the time of the accident the average age of the casualties was 32.5 years (range: 5 - 68 years). 86 % of the casualties wore a helmet while only 14 % used a body protector. 61 % of the equestrians were amateur riders and 66 % of the accidents occurred during leisure riding. 44 % of the horses were professional sport horses. 83 % of the equestrians had known the horse for over 6 months at time of injury. DISCUSSION: The qualification of the horse as well as the familiarity between rider and horse do not seem to have an effect of reducing of the number of accidents in equestrian activities. On the other hand a good education of the rider can contribute to decrease the accident rate. While the employment of helmets in riding sports has increased in recent years the use of preventive measures such as body protectors and safety education programmes are being used too rarely.

The development of the collagen fibre network in tissue-engineered cartilage constructs in vivo. Engineered cartilage reorganises fibre network.

For long term durability of tissue-engineered cartilage implanted in vivo, the development of the collagen fibre network orientation is essential as well as the distribution of collagen, since expanded chondrocytes are known to synthesise collagen type I. Typically, these properties differ strongly between native and tissue-engineered cartilage. Nonetheless, the clinical results of a pilot study with implanted tissue-engineered cartilage in pigs were surprisingly good. The purpose of this study was therefore to analyse if the structure and composition of the artificial cartilage tissue changes in the first 52 weeks after implantation. Thus, collagen network orientation and collagen type distribution in tissue-engineered cartilage-carrier-constructs implanted in the knee joints of Göttinger minipigs for 2, 26 or 52 weeks have been further investigated by processing digitised microscopy images of histological sections. The comparison to native cartilage demonstrated that fibre orientation over the cartilage depth has a clear tendency towards native cartilage with increasing time of implantation. After 2 weeks, the collagen fibres of the superficial zone were oriented parallel to the articular surface with little anisotropy present in the middle and deep zones. Overall, fibre orientation and collagen distribution within the implants were less homogenous than in native cartilage tissue. Despite a relatively low number of specimens, the consistent observation of a continuous approximation to native tissue is very promising and suggests that it may not be necessary to engineer the perfect tissue for implantation but rather to provide an intermediate solution to help the body to heal itself.

[Spine injuries due to horse riding accidents - an analysis of 30 cases]. / Reitunfallbedingte Wirbelsäulenverletzungen - eine Analyse von 30 Fällen.

INTRODUCTION: Horseback riding entails several risk factors that predispose the participant to injury. Especially craniocerebral as well as spinal trauma were common reasons for severe injuries. Hence, it is important to use effective protective gear during riding activities. However, the protective effect of actual safety vests and helmets in case of accident is still unknown. In the present study reasons, mechanisms and patterns of equine-related spine injuries were analyzed. Based on these data the effectiveness of used protective gear during accident was assessed. MATERIAL AND METHODS: 30 equestrians took part in a questionnaire survey. Based on these answered questionnaires reasons, mechanisms and patterns of equine-related injuries as well as used protective gear during accident were evaluated and analyzed. RESULTS: 24 patients (80 %) were female and 6 (20 %) were male. The median age at the time of injury was 36 years (range 14 - 72 years). The causalities suffered from 18 fractures (60 %) and 11 discoligamentous injuries (37 %), in one case a bone-bruise-injury (3 %) was found. 7 equestrians (23 %) wore a safety vest at time of injury. DISCUSSION: Despite wearing a safety vest, the spine can get damaged when accident occurred. It is not possible to create vests for equestrians capable of protecting against all spine injuries in all accidents. If the energy impact is too high, serious injuries can result, even though protective body gear is worn. But the development of improved safety vests is necessary to reduce the number of severe spine injury in the future.

Identification of molecular markers for articular cartilage.

OBJECTIVE: The aim of the current study was to identify molecular markers for articular cartilage (AC) that can be used as tools for the quality control of tissue engineered (TE) cartilage. DESIGN: A genome-wide expression analysis was performed using RNA isolated from articular and growth plate (GP) cartilage, both extracted from the knee joints of 6 weeks old minipigs. After confirming the specific expression for selected genes by RT-PCR, these were used as molecular markers for the quality control of TE cartilage. RESULTS: Albeit several known chondrocyte markers were expressed to a similar extent in articular and GP cartilage, our genome-wide expression analysis led us to identify genes being selectively expressed in either GP or articular chondrocytes. These findings led us to perform a RT-PCR expression analysis for the corresponding genes to demonstrate the absence of GP-specific markers in TE cartilage, while common or AC markers were expressed. CONCLUSIONS: Taken together, these results provide important novel insights into chondrocyte biology in general and AC in particular. In addition, it is reasonable to speculate, that some of the identified genes play distinct roles in the regulation of articular chondrocyte differentiation and/or function, thereby raising the possibility that they may serve as targets for non-operative therapies of osteoarthritis (OA).

[Risks in sport riding - a critical survey of safety standards in sport riding]. / Risikosport Reiten - eine kritische Darstellung der Sicherheitsstandards im Reitsport.

INTRODUCTION: Equitation is associated with a high rate of injuries and lethal accidents. The head is the most frequently concerned body part. Hence in the majority of the cases deaths results from head injuries. In this study injuries as well as causes of deaths were analyzed in 21 cases. Actual safety standards in equitation were appraised and suggestions for improvement were formulated. MATERIAL AND METHODS: Between 1996 and 2008 21 equestrians suffered from a fatal accident in the greater area of Hamburg. In a retrospective analysis, equestrians' records which bases on the documentation of the institute of forensic medicine as well as the insurance company ARAG were reviewed. Details of the accidents were reconstructed and pattern of injuries of those wearing a riding helmet were analyzed. RESULTS: The 21 equestrians had 29 injuries. Therefrom 86 % (18 / 21) suffered from head injuries which consequences were the causes for death. In 5 cases (24 %) equestrians wore riding helmets on the date of accident. Therefrom 80 % (4 / 5) suffered from head injuries which results in death. DISCUSSION: Actual safety standards in equitation are disappointing. The implementation of the obligation wearing a helmet as well as the improvement of the efficiency of protective clothing for equestrians is essential. Prospective studies in order to broad the state of knowledge in this context are necessary.

[Technological aspects of regenerative medicine and tissue engineering of articular cartilage]. / Technische Aspekte in regenerativer Medizin und Tissue Engineering von hyalinem Gelenkknorpel.

The main problem in the treatment of orthopaedic joint-surface defects will be solved by tissue engineering of cartilage implants. Entire biological osteochondral implants can be grown from autologous cells of the patient. The nutrition of articular cartilage is by diffusion only. Therefore the chondrocyte as the unique cell type is perfectly dedicated to the tissue culture approach. Engineering techniques of bioreactors are prerequisite for these biological and medical solutions. With our tissue engineering project for the generation of osteochondral constructs we demonstrate possibilities and characteristics of bioreactors for the modification of cell culture techniques and mechanical conditioning of cartilage tissue for fully operable implants.

[Osteoid osteoma. X-ray-controlled resection and histologic verification using a minimally invasive diamond bone-cutting system]. / Osteoidosteom. Minimal-invasive, bildwandlergesteuerte Resektion und histopathologische Diagnosesicherung mittels Diamanthohlfräsen.

BACKGROUND: In recent years, osteoid osteomas have been treated more frequently by means of percutaneous procedures. The main disadvantage in patients with suspected osteoid osteoma is the lack of histological verification. Our study presents the results that we obtained using a minimally invasive diamond bone-cutting system allowing histologic verification. MATERIALS AND METHODS: Six patients (age 10-20 years) with osteoid osteoma in the lower extremities were subjected to resection of the nidus using a minimally invasive water-cooled diamond bone-cutting system. All specimens were histologically processed and diagnosed. RESULTS: In all patients the nidus was resected successfully, and the diagnosis was histologically confirmed. The mean operating time was 22.8 min. All patients were allowed full weight-bearing immediately, and hospitalization was a maximum of 2 days. All patients were free of pain and relapse-free during the entire 2-year postoperative follow-up. CONCLUSION: In selected localizations with a clearly visible nidus, the minimally invasive diamond bone-cutting system presented here offers an alternative to the established surgical and percutaneous procedures for treating osteoid osteomas. This procedure combines the advantages of a minimally invasive technique with the option of histological verification of the diagnosis and correct nidus ablation.

Long term results after implantation of tissue engineered cartilage for the treatment of osteochondral lesions in a minipig model.

In present study we determined the long term in vivo integration and histological modeling of an in vitro engineered cartilage construct. Tissue engineered autologous cartilagenous tissue was cultured on calcium phosphate cylinders and implanted into osteochondral defects into the femoral condyles in minipigs. Radiological follow-up was performed at 2, 8, 26 and 52 weeks, condyles were harvested 26 and 52 weeks post-implantation. Thickness of cultivated tissue (1.10 +/- 0.55 mm) was comparable to in situ cartilage and cells produced in vitro cartilage specific proteins. In vivo, 26 and 52 weeks post-implantation defects were resurfaced with hyaline-like tissue, the implants were well integrated with no gap at the interface between the engineered neocartilage and the adjacent articular cartilage. Synthesis of type II collagen was detected 26 and 52 weeks after implantation. The modified ICRS score increased from 26 to 52 weeks. Histomorphometric evaluation revealed a decrease in cellularity in tissue engineered cartilage from 2.2-fold of native cartilage after 26 weeks to 1.5-fold after 52 weeks. In conclusion, these findings demonstrate the integration and maturation of tissue engineered cartilage pellets attached on a bone substitute carrier implanted in osteochondral defects over a long time.

[Outcomes research: definitions, methods and challenges in trauma and orthopaedic surgery]. / Versorgungsforschung : Bedeutung, Methoden und Herausforderungen in der Unfallchirurgie.

BACKGROUND: Besides basic, illness- and patient-oriented research, outcomes research is regarded as the fourth pillar of modern health care systems. Outcomes research investigates both the desirable and adverse effects of medical and surgical interventions under day-to-day conditions. METHOD: Because of rigorous entry criteria and selection of eligible subjects, the efficacy of a certain treatment derived from clinical experiments (i.e. classic randomized trials) may not necessarily be transferred to common patient populations or clinical settings. Apart from efficacy, a valuable (thus reimbursable) diagnostic or therapeutic procedure must prove its effectiveness in clinical practice as well. Demanding study designs are necessary to model effectiveness and to separate the observed intervention-related effects from bias and confounding. RESULTS: Registries and pragmatic randomized trials may represent the most appropriate modalities to establish outcomes research in trauma and orthopaedic surgery. Good examples for interventions still needing proof of effectiveness are kyphoplasty and vertebroplasty, navigated surgery, damage control, interlocking implants and bone growth factors. Revealing over- and undersupply, generating negative lists (i.e. interventions of questionable or almost nil effectiveness) and integrating patients as co-therapists requires networking between hospitals and private practitioners. CONCLUSION: Also, since outcomes research is a societal need, its development and funding must be ensured by all providers and payers of health care services.

Response of primary fibroblasts and osteoblasts to plasma treated polyetheretherketone (PEEK) surfaces.

Polyetheretherketone (PEEK) is a synthetic polymer with suitable biomechanical and stable chemical properties, which make it attractive for use as an endoprothetic material and for ligamentous replacement. However, chemical surface inertness does not account for a good interfacial biocompatibility, and PEEK requires a surface modification prior to its application in vivo. In the course of this experimental study we analyzed the influence of plasma treatment of PEEK surfaces on the cell proliferation and differentiation of primary fibroblasts and osteoblasts. Further we examined the possibility of inducing microstructured cell growth on a surface with plasma-induced chemical micropatterning. We were able to demonstrate that the surface treatment of PEEK with a low-temperature plasma has significant effects on the proliferation of fibroblasts. Depending on the surface treatment, the proliferation rate can either be stimulated or suppressed. The behavior of the osteoblasts was examined by evaluating differentiation parameters. By detection of alkaline phosphatase, collagen I, and mineralized extracellular matrix as parameters for osteoblastic differentiation, the examined materials showed results comparable to commercially available polymer cell culture materials such as tissue culture polystyrene (TCPS). Further microstructured cell growth was produced successfully on micropatterned PEEK foils, which could be a future tool for bioartificial systems applying the methods of tissue engineering. These results show that chemically inert materials such as PEEK may be modified specifically through the methods of plasma technology in order to improve biocompatibility.

[Indications and implementation of recommendations of the working group "Tissue Regeneration and Tissue Substitutes" for autologous chondrocyte transplantation (ACT)]. / Indikations- und Durchführungsempfehlungen der Arbeitsgemeinschaft "Geweberegeneration und Gewebeersatz" zur Autologen Chondrozyten-Transplantation (ACT).

For the treatment of full-thickness articular cartilage lesions of the knee joint, as a result of trauma or osteochondritis dissecans, a variety of biological reconstruction techniques have been developed. Different studies, some of which were performed as randomised, prospective clinical studies, showed that the autologous chondrocyte transplantation (ACT) provides the most satisfying and reliable method of cartilage reconstruction in the adult when applied to defects exceeding 4 cm (2). Based on these results, ACT seems to be of economic benefit, as the risk of developing osteoarthritis correlates significantly with the size of the cartilage defect, when not treated properly and in time. Surveying the studies on basic scientific aspects of ACT, cartilage defect animal models and clinical studies, it can be concluded that clinical results of ACT depend on a variety of factors. In this review, published by the joined advisory board of the German Societies of Traumatology (DGU) and Orthopaedic Surgery (DGOOC), we summarize the current knowledge available and the state of the art concerning ACT. Especially we discuss the advantages of different procedures, methods for treating knee cartilage defects and factors that influence the outcome of the different treatment regimens, with the aim to develop guidelines for the correct indication and application of the ACT.

[Bone grafts endoscopically applied to the spine Ergebnisse der anterioren Fusion und therapeutische Konsequenzen]. / Endoskopische Knochentransplantation an der Wirbelsäule Ergebnisse der anterioren Fusion und therapeutische Konsequenzen.

The application of autogenous bone grafts represents the golden standard for reconstruction of the load-bearing anterior column in the thoracolumbar spine. However, the osseous integration of the implanted grafts is demanding and delayed union or pseudarthrosis may occur. There are no standardized data available yet indicating the further course in such cases. The aim of this study was to evaluate the incorporation of endoscopically applied grafts and to develop therapeutic strategies for delayed or non-fusions. Twenty patients suffering from unstable injuries of the thoracolumbar spine were studied in a prospective clinical trial. After primary dorsal stabilization, the anterior column was thoracoscopically reconstructed with an autogenous iliac crest graft and a fixed-angle implant (MACS). The osseous integration of the bone grafts was detected by MSCT 1 year postoperatively. Complete integration of the transplanted bone grafts was observed in only 65% of the cases. In 25% partial integration was detected and in two cases a fracture of the transplanted iliac crest graft occurred. Despite the incomplete integration of the bone grafts, the further course without surgical intervention revealed no clinical or radiological evidence of a concomitant implant loosening or a relevant secondary loss of correction. Similar to the open technique, endoscopic reconstruction of the anterior column with autogenous bone grafts may lead to disadvantageous results concerning the integration and healing of the applied bone grafts. Decision making in such cases depends on the individual clinical and radiological findings (i.e., evidence of implant loosening and concomitant loss of correction).

[Investigation of the health-related quality of life after a dorso ventral stabilization of the thoracolumbar junction]. / Untersuchung der Lebensqualität nach dorsoventraler Stabilisierung von Wirbelkörperfrakturen des thorakolumbalen Ubergangs.

OBJECTIVE: Combined dorsoventral stabilization provides superior mechanical stability in the operative treatment of thoracolumbar spine fractures. Currently, there are no data available reflecting the quality of life in trauma patients following the combined procedure. The aim of this investigation was to study the health-related quality of life after dorsoventral stabilization of the thoracolumbar junction using the SF-36 Health Survey. METHODS: In order to assess the quality of life, 30 patients from a consecutive series with unstable fractures of the thoracolumbar junction were investigated in a clinical study. After posterior stabilization with an internal fixator (USS, Synthes),anterior arthrodesis was performed subsequently by autogenous iliac bone grafting in combination with osteosynthesis (MACS, Aesculap; VentroFix, Synthes). The quality of life was investigated 2 years after surgery. Additionally, plain X-rays were obtained and the degree of kyphotic deformation was measured. RESULTS: The evaluation of the data obtained from the SF-36 revealed a reduced quality of life, especially regarding the "physical functioning index", the "bodily pain index", and the "emotional functioning index". Of the patients, 42% still suffered from moderate to severe pain. Measurement of the Cobb angle showed a slight loss of correction without occurrence of a relevant kyphotic deformity. Our statistical analyses did not show any correlation between the data obtained from the SF-36 and the clinical results. Especially there was no correlation between the "bodily pain index" and the Cobb angle ( r=0.112, Spearman's rank order correlation). CONCLUSION: The patients studied here showed a reduced quality of life 2 years after dorsoventral stabilization of the thoracolumbar junction predominantly resulting in long-term pain symptoms. As these findings could not be related to the radiological results (i.e., the occurrence of a kyphotic deformation), other factors such as injury of the motion segment of the spine and the major surgical procedure have to be considered as the main reasons for the reduced quality of life. In summary, it can be concluded that the SF-36 is a suitable tool for the investigation of the postoperative outcome following dorsoventral stabilization of the thoracolumbar junction in trauma patients.

[Long-term outcomes after using porous hydroxyapatite ceramics (Endobon) for surgical management of fractures of the head of the tibia]. / Langzeitergebnisse nach Anwendung einer porösen Hydroxylapatitkeramik (Endobon) zur operativen Versorgung von Tibiakopffrakturen.

Endobon is a porous hydroxyapatite ceramic which has been used as a bone replacement substitute since 1989. Currently there are no data available reflecting long-term effects of Endobon in human bone grafting. In order to assess such effects 35 patients with fractures of the proximal tibia were studied retrospectively over a period up to 91 months. The metaphyseal defects were filled by Endobon and fractures were stabilized by internal plate fixation subsequently. A secondary loss of reduction due to mechanical failure of the bone replacement material did not occur even after removal of metal implants. No histological signs of resorption or degradation could be found 18 months after application. Our data show that Endobon provides good mechanical properties during a long term follow-up and can be recommended as a suitable therapeutic option versus cancellous bone graft.