Invasive electrical stimulation in the treatment of avascular osteonecrosis of the femoral head - mid-term results.

The study aimed to evaluate the outcomes of osteonecrosis of the femoral head (ONFH) in adults after surgical treatment including invasive electromagnetic osteostimulation (E-Stim). Further, the influence of disease stage and several comorbidities on the joint preservation rate should be examined. Sixty patients (66 hip joints) with ONFH were included in this retrospective cross-sectional analysis (mean follow-up: 58 months, 19-110 months). Potential ONFH risk factors and comorbidities (ONFH stage, age, sex, alcohol, smoking, cortisone medication, chemotherapy) were recorded. The influence of specific parameters on the joint preservation rates was evaluated by a multivariate logistic regression analysis. Finally, patients with preserved hip joints underwent an assessment of their last available X-rays. The joint preservation rate depended on the initial ONFH Steinberg stage (I+II: 82.8%, III: 70.8%, ≥ IVa: 38.5%). Initially collapsed ONFH (p ≤ 0.001) and cortisone therapy (p = 0.004) significantly decreased the joint preservation rates. In case of progressed ONFH, the presence of ≥ 2 risk factors resulted in higher THA conversion rates (stage III: OR 18.8; stage ≥IVa: OR 12). In 94% of the available X-rays, the ONFH stage improved or did not progress. No complications could be attributed to the E-Stim device or procedure. The present surgical protocol including minimally invasive E-Stim revealed high joint preservation rates for non-collapsed ONFH after mid-term postoperative follow-up. Especially in progressed ONFH, the-risk profile seems to be crucial and hence, for joint preserving surgery, careful patient selection is recommended.

[Premature wear of total knee arthroplasty in sports shown in a golfer]. / Vorzeitiger Verschleiß von Knieendoprothesen im Sport am Beispiel eines Golfers.

Sport with an endoprosthesis is controversially discussed, whereas golf with a knee endoprosthesis is usually allowed. This case shows that playing golf can lead to severe wear of the prosthesis. The wear pattern of the components of the prosthesis suggests increased rotational loads. A change to a constrained prosthesis was made because of metal-to-metal contact. It is important to inform the patient before surgery about sports with endoprosthesis. Athletic loads are not part of prosthesis testing according to ISO.

[What do orthopedic and trauma surgeons expect from radiologists when interpreting imaging of the elbow?] / Was erwarten Orthopäden und Unfallchirurgen vom Radiologen bei der Beurteilung der Bildgebung des Ellenbogens?

CLINICAL ISSUE: The elbow is a complex joint with a multitude of acute and chronic pathologies. In addition to the clinical examination, radiological diagnostics play a decisive role in the further therapeutic management. DIAGNOSTIC WORK-UP/PERFORMANCE: While acute traumatic injuries often present with obvious structural changes and the need for rapid treatment decisions, chronic processes can present with less evident alterations. Especially in these cases there is a need for clear communication between the treating physician and the radiologist with respect to managing optimal imaging as the basis for a certain diagnosis and therefore optimal treatment. Basic prerequisites on both sides are detailed knowledge of all elbow pathologies, classifications and the spectrum of radiological diagnostic imaging. ACHIEVEMENTS/PRACTICAL RECOMMENDATIONS: From the point of view of orthopedic surgeons the radiologist is responsible for the correct performance and interpretation of the necessary imaging procedures. The aim of this article is to give an overview of important aspects in the imaging of typical orthopedic/traumatic pathologies.

[Handling of retrieved implants in orthopedic surgery : Results of a survey within the framework of the EndoCert initiative]. / Bestandsaufnahme zum Umgang mit ausgebauten Implantaten in der orthopädischen Chirurgie : Ergebnisse einer Umfrage im Rahmen der EndoCert-Initiative.

BACKGROUND: Although investigations of retrieved medical implants can provide valuable information about the cause of the revision, there is a lack of information, which could be avoided by consequent failure analyses. In the framework of the EndoCert certification system it is obligatory to record and report incidents. OBJECTIVES: The present work examines how the willingness to report has developed in certified arthroplasty centers and which method of handling retrievals is preferred and actually used. MATERIALS AND METHODS: On the basis of a questionnaire for handling retrievals, all 508 arthroplasty centers that were certified till June 1, 2016, were included (return rate = 97.2%). RESULTS: A total of 93.3% of the centers have established an algorithm for handling of retrievals and 83.0% of the centers prefer to hand out the retrieval to the patient, while only 25.7% wish to store it in the center for research purposes. In the case of a potential incident as the cause of revision, centers prefer to forward the retrieval to damage analysis, whereby the centers act in different ways, depending on the case. An implant fracture is, e.g., considered a reportable event in most cases without temporal limitation. On the other hand, breakage or failure of surgical instruments is considered not to be reported in the case of more than half of the centers. In 2014 and 2015, approximately 71% of EPZs reported no incidents. CONCLUSIONS: According to our survey, many certified arthroplasty centers are sensitized to careful handling of retrievals. The treatment of the explanted components is conducted in different ways. The assessment of whether an incident is to be reported shows large differences. In view of the relatively high number of revision surgeries, the number of reports to the authorities appears to be low.

Predictors of colonization with Staphylococcus species among patients scheduled for cardiac and orthopedic interventions at tertiary care hospitals in north-eastern Germany-a prevalence screening study.

As methicillin-resistant Staphylococcus aureus (MRSA) colonization and infection in humans are a global challenge. In Mecklenburg and Western Pomerania (Germany) 1,517 patients who underwent surgical interventions were systematically screened for MRSA and MSSA colonization on the day of hospital admission and discharge. Demographic data, risk factors and colonization status of the (i) nose, (ii) throat, (iii) groin, and (iv) thorax or site of surgical intervention were determined. Of the 1,433 patients who were included for further evaluation, 331 (23.1%) were colonized with MSSA, while only 17 (1.2%) were MRSA carriers on the day of hospital admission. A combination of nose, throat and groin swabs returned a detection rate of 98.3% for MSSA/MRSA. Trauma patients had lower prevalence of MRSA/MSSA (OR 0.524, 95% CI: 0.37-0.75; p < 0.001) than patients with intended orthopedic interventions. Males showed significantly higher nasal S. aureus carrier rates than females (odds ratio (OR) = 1.478; 95% CI: 1.14-1.92; p = 0.003). Nasal S. aureus colonization was less frequent among male smokers as compared to non-smokers (chi2 = 16.801; phi = 0.154; p < 0.001). Age, gender and smoking had a significant influence on S. aureus colonization. Combining at least three different swabbing sites should be considered for standard screening procedure to determine S. aureus colonization at patients scheduled for cardiac or orthopedic interventions at tertiary care hospitals.

[Injuries in Karate Sports: A Survey Performed During the World Championship 2014]. / Verletzungen im Karatesport ­ eine Umfrage während der Weltmeisterschaft 2014.

Background: In literature, the competitive sport of modern karate is almost always characterised as a combat sport involving injuries caused by impact effects and physical contact with opponents. There is a lack of data regarding the outcome after karate injuries, specifically with a view to the contact-free Kata karate. Methods: Performing a random test using a questionnaire, we collected data concerning regular medical treatment, prior surgeries of the locomotor system, and medical care. This study included 300 athletes from 65 countries (average age: 24.1 years; 176 male, 124 female) participating in the Karate World Cup 2014. Seven participants competed in both disciplines, 87 only in the Kata discipline, and 206 only in Kumite (the discipline involving physical contact with opponents). The statistical analysis was performed using a two-sided Chi-square test and the Fisher's exact test. Results: Recurrent medical treatment was most commonly required for the knee region (Kata 28.7 %, Kumite 26.7 %). In Kata the shoulder region came second (22.9 %), in Kumite the ankle region (21.8 %), followed by hand and foot in both groups. Medical treatment of the elbow area was more frequent in the Kata Group (p = 0.033), while in Kumite athletes' hand (p = 0.002) and foot injuries (p = 0.007) prevailed. Prior surgeries of athletes of both disciplines most commonly concerned the knee, followed by the ankle region in the Kata group and by the hand and head region in the Kumite group. Statistically significant differences between the two disciplines were found in head injuries (p = 0.004), which commonly do not occur in the Kata discipline. During the World Cup, 56.0 % of the athletes had no individual medical care and 24.6 % received no sports-related medical care in their home countries. Conclusion: Although the risk of injuries in Kumite Karate has been reduced by the introduction of gumshields, hand and foot protectors as well as a reform of the scoring system, the potential for chronic physical damage should not be underestimated. Since in athletes competing in the Kata discipline the rate of surgeries and injuries is only slightly lower than in the Kumite group, Kumite Karate may be regarded as a martial arts competitive sport with a relatively low risk of injuries. In contrast, the risk of chronic musculoskeletal damage in Kata athletes seems to be underestimated thus far. Suggested improvements concern the training techniques and conditions (i. e. the tatami material), and there is a need for regular medical care, including preventative care, to be provided for these athletes.

Potential infection control risks associated with roaming healthcare industry representatives.

BACKGROUND: Healthcare industry representatives (HCIR) visit multiple hospitals every day. Most enter hygiene sensitive areas and work in close proximity to caregivers and patients. OBJECTIVE: The objective of the present study was to evaluate the HCIRs' current status in hygiene training and vaccination. METHODS: An anonymous walking intercept study was used based on questionnaires to evaluate industry representatives in comparison to physicians and nurses (n = 311 participants, participation rate 30.2%) after their visit to the MEDICA Congress. The valid participants consisted of HCIR (n = 208), hospital nurses (n = 49) and physicians (n = 41). A total of 82.2% (n = 171) HCIR worked in varying hospitals. RESULTS: They frequently request access to hygiene and data-privacy sensitive areas: Among them 51.9% (n = 108) accessed the outpatient clinic, 41.8% (n = 87) the operating room (OR), 33.7% (n = 70) the central supply and sterilisation department (CSSD), and 32.7% (n = 68) the intensive care unit. HCIR requesting access to hygiene sensitive areas showed the lowest scores in hygiene training and a significantly lower Hepatitis B vaccination status, i.e. 37.5% compared to 70.7% for physicians and 53.1% for nurses. DISCUSSION: Status of HCIR hygiene training was inadequate - as was vaccination and contamination control. Therefore, HCIR are exposed to increased infection risk and may unknowingly act as infection vector between different hospitals.

[Quality of Outcome after Primary Total Hip Replacement at a Maximum Care Hospital in Relation to Preoperative Influencing Factors]. / Ergebnisqualität nach Hüftendoprothesen-Erstimplantation an einem Krankenhaus der Maximalversorgung in Bezug auf präoperative Einflussfaktoren.

BACKGROUND: As the need for joint replacements will continue to rise, the outcome of primary total hip replacement (THR) must be improved and stabilised at a high level. In this study, we investigated whether pre-operative risk factors, such as gender, age and body weight at the time of the surgery or a restricted physical status (ASA-Status > 2 or Kellgren and Lawrence grade > 2) have a negative influence on the post-operative results or on patient satisfaction. MATERIAL AND METHODS: Retrospective data collection and a prospective interview were performed with 486 patients who underwent primary total hip replacement between January 2007 and December 2010 in our hospital. The patients' satisfaction and quality of life were surveyed with the WOMAC-Score, SF-36 and EuroQol-5. Differences between more than two independent spot tests were tested with the non-parametric Kruskal-Wallis test. Differences between two independent spot tests were tested with the non-parametric Mann-Whitney U test. The frequencies were reported and odds ratios calculated. The confidence interval was set at 95 %. The level of significance was p < 0.05. RESULTS: The average WOMAC-Score was 77.1 and the total score of the SF-36 was 66.9 points. The patients declared an average EuroQol Index of 0.81. Our data show that the patients' gender did not influence the duration of surgery or the scores. However, female patients tended to exhibit more postoperative complications. However, increased patient age at the time of surgery was associated with an increased OR for duration of surgery, length of stay and risk of complications. Patients who had a normal body weight at time of the surgery showed better peri- and post-operative results. We showed that the preoperative estimated Kellgren and Lawrence grade had a significant influence on the duration of surgery. The ASA classification influenced the duration of surgery as well the length of stay and the rate of complications. CONCLUSION: The quality of results after primary THR depends on preoperative factors. Existing comorbidities have a significant influence on the duration of surgery and therefore on the perioperative rate of complications and the postoperative outcome. Despite improvements in the functional and subjective outcome after primary THR, an adverse preoperative symptomatic status is associated with less favourable postoperative results.

[Hybrid and uncemented hip arthroplasty: Contribution margin in the German lump sum reimbursement system]. / Teilzementierte und unzementierte Hüftendoprothetik: Deckungsbeitrag im deutschen Fallpauschalensystem.

BACKGROUND: The economization of inpatient care began when lump sum reimbursement was introduced into the hospital sector. Since then, total hip arthroplasty (THA) has experienced a rapid development in terms of annual procedures and the optimization of the clinical pathway. Therefore, it is obvious to highlight THA as one of the most common procedures in the German health care system. In this work, the two most common techniques for the fixation of THA are investigated with regard to their cost structure and their influence on the clinical result. OBJECTIVES: In Germany, uncemented and hybrid fixation are used for THA. In this study we investigated the differences in material costs, the duration of surgery, and the length of stay. MATERIALS AND METHODS: For each fixation technique a retrospective cost analysis was carried out, based on the data from the treatment documentation of the University Hospital for Orthopedics, Rostock (OUK). The mean values of the parameters and expenses have been reviewed with descriptive statistics for differences. RESULTS: With regard to total costs and the contribution margin there was no statistically significant difference. CONCLUSIONS: Although there are differences in individual cost areas, in total costs, cost advantages and disadvantages cancel each other out. Thus, from an economic perspective no particular technique can be recommended.

[Implementation of the EndoCert system for certification of arthroplasty centers. Experiences from the pilot phase]. / Die Einführung des EndoCert-Systems zur Zertifizierung von Endoprothesenzentren. Erfahrungen aus der Pilotphase.

BACKGROUND: EndoCert is an initiative of the Deutschen Gesellschaft für Orthopädie und Orthopädische Chirurgie (DGOOC, German Society for Orthopedics and Orthopedic Surgery) which has been available since October 2012 and is the first system worldwide for certification of specialized arthroplasty centers. Before implementation of this certification concept two sequential pilot phases were carried out with representative treatment institutions. The results from these pilot clinics are presented with respect to quality improvement effects. NONCONFORMITIES: Early effects on the quality of treatment have been achieved by rectification of nonconformities determined in the audit with respect to structural and process quality. A total of 172 nonconformities found in the 23 participating pilot clinics could be rectified. Long-term effects on the quality of results will in future be analyzed in cooperation with the German endoprosthesis register (EPRD) and by accompanying evaluations. FEEDBACK: A close feedback of the collated experiences and results to the certification committee, which is responsible for the procedure together with the DGOOC, allows continuous further development of the system CONCLUSION: EndoCert represents a substantial step towards a nationwide safety and improvement of the quality in arthroplasty treatment within the preoperative, perioperative and postoperative framework and can in future represent a decisive tool together with the EPRD in quality management.

[Reportable incidents with surgical instruments in orthopedic surgery]. / Meldepflichtige Vorkommnisse mit Operationsinstrumenten in der Orthopädischen Chirurgie.

BACKGROUND: Breakage of instruments in orthopedic surgery is rarely reported but the consequences can be serious for both patients and surgeons. The medical device directive classifies instruments, such as drills and saws into risk class 1 with low approval requirements. Also the number of applications of reusable instruments is not currently limited. OBJECTIVES: The aim of this study was determine to what extent instrument failure can lead to reportable incidents and how these incidents should be processed. METHODS: The study involved an evaluation of clinical cases from our institution with a selective literature review and discussion of the medical device directive. RESULTS: The experience in our clinic showed that especially breakage of rasps in total hip and knee replacement surgery is associated with a major time extension of the operational procedure, a wider surgical access opening as well as complicated procedures to recover the fragments from the incident site. In individual cases a fenestration of the bone had to be conducted in order to collect the broken piece of the rasp. In one case a revision hip stem had to be used instead of the planned primary stem in order to bridge the fenestration site. CONCLUSION: Such consequences of instrument failure were considered to be a reportable incident. A thorough documentation as well as incident reporting to the manufacturer and the Federal authorities are required for a sufficient processing and risk assessment of the incident.

Establishment of a novel in vitro test setup for electric and magnetic stimulation of human osteoblasts.

When large defects occur, bone regeneration can be supported by bone grafting and biophysical stimuli like electric and magnetic stimulation (EMS). Clinically established EMS modes are external coils and surgical implants like an electroinductive screw system, which combines a magnetic and electric field, e.g., for the treatment of avascular bone necrosis or pseudarthrosis. For optimization of this implant system, an in vitro test setup was designed to investigate effects of EMS on human osteoblasts on different 3D scaffolds (based on calcium phosphate and collagen). Prior to the cell experiments, numerical simulations of the setup, as well as experimental validation, via measurements of the electric parameters induced by EMS were conducted. Human osteoblasts (3 × 10(5) cells) were seeded onto the scaffolds and cultivated. After 24 h, screw implants (Stryker ASNIS III s-series) were centered in the scaffolds, and EMS was applied (3 × 45 min per day at 20 Hz) for 3 days. Cell viability and collagen type 1 (Col1) synthesis were determined subsequently. Numerical simulation and validation showed an adequate distribution of the electric field within the scaffolds. Experimental measurements of the electric potential revealed only minimal deviation from the simulation. Cell response to stimulation varied with scaffold material and mode of stimulation. EMS-stimulated cells exhibited a significant decrease of metabolic activity in particular on collagen scaffolds. In contrast, the Col1/metabolic activity ratio was significantly increased on collagen and non-sintered calcium phosphate scaffolds after 3 days. Exclusive magnetic stimulation showed similar but nonsignificant tendencies in metabolic activity and Col1 synthesis. The cell tests demonstrate that the new test setup is a valuable tool for in vitro testing and parameter optimization of the clinically used electroinductive screw system. It combines magnetic and electric stimulation, allowing in vitro investigations of its influence on human osteoblasts.

[Influence of surgeon experience in total hip arthroplasty. Dependence on operating time and complication risk]. / Einfluss der Erfahrung des Operateurs in der Hüftendoprothetik. Abhängigkeit von Operationsdauer und Komplikationsrisiko.

BACKGROUND: As a consequence of limited personnel and financial resources, the increase in total hip arthroplasties places higher demands on orthopedic surgeons. OBJECTIVES: In order to maintain high quality treatment, the correlation between surgical experience, duration of surgery and risk of complications was examined. MATERIAL AND METHODS: The surgery time and, if applicable, complications (until discharge from hospital) of 1129 total hip arthroplasties over a period of 4 years were evaluated retrospectively. RESULTS: The group of most experienced surgeons needed an average time of 53.2 ± 17.6 min for each implantation, followed by moderately experienced surgeons (74.5 ± 25.5 min) and less experienced surgeons (80.8 ± 21.9 min). Of all included cases, a total of 41 complications until discharge from hospital occurred. The number of complications increased with duration of surgery, whereby the risk of complications was significantly lower for shorter surgery times conducted by the most experienced surgeons as well as moderately experienced surgeons. The complication risk of less experienced surgeons remained constant independent of surgery duration. CONCLUSION: These results underline the recommendations of the German Endocert system, which determine a minimum number of total joint arthroplasties as a quality indicator not only for hospitals but also for individual surgeons.

[Failure analysis as basis for quality assurance strategies in implant technology]. / Schadensanalyse als Basis für Qualitätssicherungsstrategien in der Implantattechnologie.

BACKGROUND: Implant safety is a topic gaining more and more public interest. Implants are safety relevant medical devices which in the case of failure can lead to life-threatening situations. OBJECTIVES: A well-founded failure analysis requires expert knowledge not only of materials and implant design but also a qualified explantation procedure and storage conditions. METHODS: A selective literature search was carried out putting the main emphasis on implant failure analysis supplemented with own investigations. RESULTS: The reasons for implant breakdown are mostly failures of materials and in the manufacturing process. In some cases false material combinations can lead to tribocorrosion effects under cyclic loading. CONCLUSION: The increased level of knowledge gained from complex analyses of failed implants produces valuable evidence for better quality management.

[Logbook of learning targets for special educational skills in orthopaedic and trauma surgery for undergraduate medical training]. / Logbuch der erreichbaren Lehrziele für die speziellen Wahlfachinhalte Orthopädie/Unfallchirurgie im Praktischen Jahr (PJ) des Medizinstudiums.

INTRODUCTION: The changes in medical licensing regulations introduced in Germany in 2012 require the development of specific catalogues, termed logbooks, that define the practical skills medical students should acquire in different specialties. In conjunction with another change in medical education, which allows medical students to freely select any German university hospital or academic teaching hospital for their one-year internship, these catalogues are a prerequisite for ensuring comparable training standards throughout Germany. The German licensing regulations provide no details regarding the contents or form of the logbooks but only mention a "training programme" in very general terms. A logbook is commonly understood to define clear learning objectives to be accomplished during a specified interval (4 months). The conference of German medical faculties proposed a basic logbook for compulsory training modules (surgery and internal medicine) that is intended to serve as a model (formally and contentwise) for those who develop similar catalogues for elective training modules. Here we present our logbook for an elective training module in orthopaedic surgery and traumatology. MATERIAL AND METHOD: The logbook presented here is based on the catalogue of learning outcomes in orthopaedic surgery and traumatology developed by an expert board of the medical teaching study group of the German Society of Orthopaedic Surgery and Traumatology (DGOU) in 2011. The objectives defined for the one-year internship are of necessity divided into orthopaedic surgery and traumatology skills that must be acquired by all medical students and those that are optional (compulsory and elective modules). Using a set of predefined criteria, the authors developed the catalogue of learning outcomes (logbook) presented here. The catalogue outlines the competencies to be acquired in an elective orthopaedic surgery and traumatology module, leaving it to each medical faculty to work out the details. Where applicable, comprehensive skills across a number of (compulsory and elective modules) learning objectives are arranged in such a way that they can be taught at different levels of complexity. RESULTS: The logbook covers 15 skill domains from different specific components of orthopaedic surgery and traumatology. Where these skills overlap with those also required in compulsory modules (e.g., surgery), the required level of complexity may be lower for students in the elective module. The text is supplemented by figures with synopses of the major issues and summaries for easy reference. CONCLUSION: With the recent changes in German licensing regulations for physicians, it has become necessary to set up a logbook of uniform learning outcomes to assist medical students and their teachers alike. The authors have developed such a logbook of elective training modules in orthopaedic surgery and traumatology to be taught during the one-year undergraduate internship of German medical students.

Scaffold-assisted cartilage tissue engineering using infant chondrocytes from human hip cartilage.

OBJECTIVE: Studies about cartilage repair in the hip and infant chondrocytes are rare. The aim of our study was to evaluate the use of infant articular hip chondrocytes for tissue engineering of scaffold-assisted cartilage grafts. METHOD: Hip cartilage was obtained from five human donors (age 1-10 years). Expanded chondrocytes were cultured in polyglycolic acid (PGA)-fibrin scaffolds. De- and re-differentiation of chondrocytes were assessed by histological staining and gene expression analysis of typical chondrocytic marker genes. In vivo, cartilage matrix formation was assessed by histology after subcutaneous transplantation of chondrocyte-seeded PGA-fibrin scaffolds in immunocompromised mice. RESULTS: The donor tissue was heterogenous showing differentiated articular cartilage and non-differentiated tissue and considerable expression of type I and II collagens. Gene expression analysis showed repression of typical chondrocyte and/or mesenchymal marker genes during cell expansion, while markers were re-induced when expanded cells were cultured in PGA-fibrin scaffolds. Cartilage formation after subcutaneous transplantation of chondrocyte loaded PGA-fibrin scaffolds in nude mice was variable, with grafts showing resorption and host cell infiltration or formation of hyaline cartilage rich in type II collagen. Addition of human platelet rich plasma (PRP) to cartilage grafts resulted robustly in formation of hyaline-like cartilage that showed type II collagen and regions with type X collagen. CONCLUSION: These results suggest that culture of expanded and/or de-differentiated infant hip cartilage cells in PGA-fibrin scaffolds initiates chondrocyte re-differentiation. The heterogenous donor tissue containing immature chondrocytes bears the risk of cartilage repair failure in vivo, which may be possibly overcome by the addition of PRP.

[Arthroscopically assisted therapy of avascular necrosis of the femoral head]. / Arthroskopisch gestützte Behandlung der aseptischen Hüftkopfnekrose.

OBJECTIVE: Preservation of the hip joint function by treatment of the avascular necrosis of the femoral head in adults or at least avoiding progression. INDICATIONS: Avascular necrosis of the femoral head in adults in Steinberg stages I-III. In patients with Steinberg stage IVa (subchondral collapse ≤ 15% of the articular surface, depression < 2 mm) hip joint salvage therapy in early stages of femoral head collapse. CONTRAINDICATIONS: Manifest osteoarthritis of the hip joint. Joint infection. Relative contraindications: subchondral collapse > 15% of the articular surface or depression > 2 mm (Steinberg stage IVb and above). Persisting risk factors for a progression of avascular necrosis (e.g., alcohol abuse, chemotherapy, local irradiation, high-dose cortisone therapy) and obesity (BMI > 40). SURGICAL TECHNIQUE: Arthroscopy of the hip joint in case of cartilage defects and/or potential collapse of the femoral head. Without collapse of the femoral head and absence of severe damage of the cartilage: core decompression using a guiding sleeve through a lateral approach (Steinberg II, III). Subsequently curettage of the necrotic area through a central drill hole and insertion of autogenic bone cylinders using an OATS harvester (Steinberg II b/c, III b/c). In Steinberg stage IVa, reconstruction of the outline of the femoral head is attempted by reduction of the impressed portion (under intraoperative fluoroscopy). POSTOPERATIVE MANAGEMENT: Limited weight bearing (10 kg) of the operated leg for 6 weeks. In cases of large necrotic defects located directly beneath the subchondral bone (Steinberg IIIc) as well as subchondral collapse with flattening of the femoral head (Steinberg IVa) limited weight bearing (10 kg) for 12 weeks. RESULTS: Early results of femoral head preserving therapy in 53 patients (56 hips, consecutively treated between June 2004 and December 2009) after 33 ± 20 months: success rate (no arthroplasty, no reoperation, no radiological progress associated with clinical symptoms) 86% for patients treated with Steinberg stages I-III. Failure of the head preserving therapy with concern to the mentioned criteria depending on the initial Steinberg stage: 0 (0%) for stage I, 2 (10%) for stage II, 3 (25%) for stage III, and 4 (31%) for stage IVa.