Maximizing the Utility of Alzheimer's Disease Trial Data: Sharing of Baseline A4 and LEARN Data.

BACKGROUND: The Anti-Amyloid Treatment in Asymptomatic Alzheimer's Disease (A4) and Longitudinal Evaluation of Amyloid Risk and Neurodegeneration (LEARN) studies were conducted between 2014 and 2023, with enrollment completed in 2017 and final study results reported in 2023. The study screening process involved the collection of initial clinical, cognitive, neuroimaging, and genetic measures to determine eligibility. Once randomized, enrolled participants were assessed every four weeks over a 4.5-year follow-up period during which longitudinal clinical, cognitive, and neuroimaging measures were collected. A large number of longitudinal fluid biospecimens were also collected and banked. Consistent with the NIH data sharing policy and the principles of Open Science, the A4/LEARN investigators aimed to share data as broadly and early as possible while still protecting participant privacy and confidentiality and the scientific integrity of the studies. OBJECTIVES: We describe the approach, methods, and platforms used to share the A4 and LEARN pre-randomization study data for secondary research use. Preliminary results measuring the impact of these efforts are also summarized. We conclude with a discussion of lessons learned and next steps. DESIGN: The materials shared included de-identified quantitative and image data, analysis software, instruments, and documentation. SETTING: The A4 and LEARN Studies were conducted at 67 clinical trial sites in the United States, Canada, Japan, and Australia. PARTICIPANTS: The A4 study screened (n=6763), enrolled, and randomized (n=1169) participants between the ages of 65 and 85 with a blinded follow-up period of 240 weeks followed by an open-label period of variable length. The LEARN study screened and enrolled individuals (n=538) who were ineligible for the A4 study based on nonelevated measures of amyloid accumulation using positron emission tomography imaging (amyloid PET). MEASUREMENTS: We provide descriptive measures of the data shared and summarize the frequency, characteristics, and status of all data access requests submitted to date. We evaluate the scientific impact of the data-sharing effort by conducting a literature search to identify related publications. RESULTS: The A4 and LEARN pre-randomization study data were released in December 2018. As of May 8, 2024, 1506 requests have been submitted by investigators and citizen scientists from more than 50 countries. We identified 49 peer-reviewed publications that acknowledge the A4/LEARN study. CONCLUSIONS: Our initial results provide evidence supporting the feasibility and scientific utility of broad and timely sharing of Alzheimer's disease trial data.

Treatment outcome of the Masquelet technique in 195 infected bone defects-A single-center, retrospective case series.

BACKGROUND: The Masquelet technique is a surgical procedure for the reconstruction of bone defects. During the first step, an osteosynthetically stabilized defect is filled with a cement spacer. The spacer induces a foreign body membrane, called a Masquelet membrane. In a follow-up procedure, the spacer is replaced by a bone graft, which ossifies in the subsequent phase. MATERIAL AND METHODS: A total of 171 patients with 195 septic bone defects on the extremities that had been treated with the Masquelet procedure at the BG Klinikum in Hamburg, Germany, from 2011 to 2021 were retrospectively analysed, comparing patients who reached full weight and load bearing on the affected extremity to those who failed to do so. Defect size and configuration, microbiological results and treatment methods as well as comorbidities and epidemiologic data were analysed for factors influencing the treatment outcome. RESULTS: In all, 113[66%] of the patients were male, and 58[34%] were female, with an age distribution of 52 +/-16 years. Out of 171 patients, 24 patients had two defects. The number of patients that reached full weight bearing was 152[89%], the follow-up period was 2 +/-1 years (median +/- SD). Full weight bearing capability was negatively by the defect size as defects >62 mm tended to be less likely to reach full weight bearing than smaller defects. A secondary stabilization with an internal stabilization was applied in 58[34%] of all patients and positively influenced the attainment of full weight and load bearing. DISCUSSION: With 171 patients and 195 septic bone defects treated at a single centre with the Masquelet Technique, this study represents a comparably large cohort. Demographics, defect characteristics and treatment outcomes did not differ from those of other cohorts described in the literature. Defects larger than 62 mm showed lower chances to reach full weight bearing and can be defined as "critical defect size" for the Masquelet technique based on our data.

[Removal of a bent femoral nail : Case report: treatment strategy of a complex femoral deformity with a bent femoral nail in situ since 36 years]. / Entfernung eines verbogenen Femurnagels : Kasuistik: Behandlungsstrategie einer komplexen Femurdeformität mit einem seit 36 Jahren einliegenden, verbogenen Femurnagel.

To remove a bent femoral nail is always a challenging task for a surgeon. In the last 20 years several case reports and descriptions of techniques are to be found in literature, the goal being to weaken the nail at the apex and then straightening it in situ in most cases. Those reports all have one parameter in common: the necessity to remove the nail relates to a refracture of the femur.We report the case of a patient who presented with the explicit wish to have a bent femoral nail removed and a femoral angulation corrected because of pain in the ipsilateral hip. A femoral fracture had been treated by a Küntscher nail in 1982. A refracture with severe bending of the nail had occurred a short time later, which was treated conservatively without a second surgical procedure.We can show that a planned removal of a bent and well-osseointegrated Küntscher nail can be achieved without complications and that thereby a multiplane angulation in the femur can be corrected, paving the way for a future arthroplasty in this specific case.

Comparison of hamstring and quadriceps tendon autografts in anterior cruciate ligament reconstruction with gait analysis and surface electromyography.

BACKGROUND: Anterior cruciate ligament (ACL) tear is the most frequent ligamentous injury of the knee joint. Autografts of hamstring (HS) or quadriceps tendons (QT) are used for primary ACL reconstruction. In this study, we planned to examine whether harvesting an HS graft is related to a deficit in dynamic knee stabilisation and strength revealed by dynamic valgus as compared with QT graft or the uninjured leg. Furthermore, if this deficit exists, is it compensated by higher neuromuscular activity of the quadriceps muscle? MATERIALS AND METHODS: Adult patients who had undergone ACL reconstruction with QT or HS autografts were included in this two-armed cohort study. Clinical outcome was assessed by clinical data analysis, physical examination and the Lysholm Score and Knee Injury and Osteoarthritis Score (KOOS). In addition, gait analysis and non-invasive surface electromyography were performed. RESULTS: A complete data set of 25 patients (QT: N = 8, HS: N = 17) was analysed. There was no significant demographic difference between the groups. Time between surgery and follow-up was significantly longer for the QT group. Significant differences regarding clinical outcome were not found between the treated and untreated leg or between the two groups, with excellent scores at the time of follow-up. Gait analysis revealed no significant differences of varus-valgus angles. Significant differences in surface electromyography were only found in the QT group with increased vastus medialis obliquus activity of the treated legs (p < 0.01). CONCLUSIONS: Our results suggest that harvesting of HS grafts for primary ACL reconstruction will not lead to a medial collapse and consequently impaired medial stabilisation of the knee when compared with QT grafts. LEVEL OF EVIDENCE: IV.

[Who Stays Loyal to Orthopaedics and Trauma Surgery? Results of a Nationwide Survey]. / Wer bleibt nach einer Famulatur in Orthopädie und Unfallchirurgie dem Fachbereich treu? Ergebnisse einer bundesweiten Umfrage.

INTRODUCTION: The general shortage of medical doctors in Germany can also be felt in the area of trauma and orthopaedics. Medical elective placements, in Germany known as "Famulatur", are sensitive interfaces between the theoretical university studies and the practical medical workplace. In this research project, the aim was to study how medical students perceive these types of placements and if it alters their decision making when planning their further career. METHODS: During the summer term of 2012, 9079 medical students answered an online questionnaire. Of these, the subgroup was evaluated that had had a placement of at least 4 weeks in the field of trauma and orthopaedics. Overall, 37 test items about this placement and further career steps were included in this study. Groups were evaluated separately by the item "I am considering a career in trauma and orthopaedics" (PJ-Ja) versus "I am not considering a career in trauma and orthopaedics" (PJ-Nein). RESULTS: Overall 397 students were included in this study; 55 % were female. 267 (67.3 %) stated: "I am considering a career in trauma and orthopaedics"; 130 (32.7 %) were not. There was no significant difference in age or sex between these groups (sex: χ²= 2.50, p = 0.114; age: F[1.93]< 1, p = 0.764). Specific and statistically significant differences between those groups were found in the items team integration, ward climate, qualification of teaching, training for specific knowledge in the field, practical aspects of the tasks performed, general planning and structure of the elective achievement of the teaching goals. DISCUSSION: Knowledge of satisfaction during medical elective placements is essential if one aims to inspire students for a specific medical profession. Instructors who can identify weaknesses and deficits in their training regime can therefore in the future increase the number of medical doctors who choose their speciality. The foundation of personal development has to be laid very early in the career of medical students.

In-vitro evaluation of surgical helmet systems for protecting surgeons from droplets generated during orthopaedic procedures.

BACKGROUND: Operating theatres and surgical clothing are designed to protect the patient from surgical site infections. However, there is still a risk of infection of the surgical team with blood-borne pathogens via ocular or mucocutaneous exposure. Whereas conventional surgical clothing provides some protection against contamination, surgical helmet systems (SHS) are intended to provide a high level of protection by forming a barrier for particles, aerosols and fluids between surgeon and surgical field of work. AIM: The aim of this study was to quantify the contamination of the surgeon by droplets during orthopaedic procedures by an in-vitro simulation of hip and knee arthroplasty while wearing SHS versus conventional surgical clothing. METHODS: Hip and knee arthroplasty procedures were performed on artificial foam bone, which was continuously kept wet with a marker fluid. Each of the procedures was carried out by ten subjects wearing conventional surgical clothing or wearing SHS with integrated toga. After the simulated operation, pictures of the subjects were taken under ultraviolet illumination. Images wearing the full gown, and after removal of the gown, were evaluated for stained areas. FINDINGS: The contamination risk was 30% while wearing conventional clothing. In none of the 20 subjects using the SHS stains could staining be detected after removal of the protective clothing. CONCLUSION: This study has demonstrated that the protective properties of the SHS are superior to conventional surgical clothing. Using SHS in high-risk procedures could reduce occupational exposure to blood-borne infections in surgeons.

Complications in Treatment of 31-A Fractures with Trochanteric Gamma Nail (TGN) Versus Gamma3 Nail (G3N) - A Review of 217 Cases.

INTRODUCTION: The aim of this study was to clinically evaluate two generations of intramedullary gamma-nail used in the treatment of 31-A femur fractures. MATERIALS AND METHODS: In two consecutive series, 117 trochanteric gamma nails (TGN) and 100 Gamma3 nails (G3N) were implanted for the treatment of inter- and subtrochanteric fractures between 2009 and 2011. Clinical and radiological follow-up examinations were assessed. An analysis of surgical time, hemoglobin drop and complications were performed. RESULTS: Average surgical time, fluoroscopy time, haemoglobin drop and length-of-stay (LOS) were similar in both groups. No significant differences were found in surgery-related complications like wound hematomas (p=0,59), abscesses (p=0,38), wound infections (p=0,69) and Cut-outs (p=0,69) between the two groups. The cumulative surgery-related complication rate was higher in the TGN group compared to the G3N group (13,68% vs. 8%) but this did not reach statistical significance (p=0,2). CONCLUSION: Our findings suggest that both TGN and G3N allow adequate treatment of trochanteric fractures with an acceptable complication rate.

Traumatic Rupture of the Distal Triceps Tendon (A Series of 7 Cases).

Even non-traumatic ruptures of the triceps tendon are rare, surgical therapy should be recommended in all cases, because of poor results after non-operative treatment. A golden standard for the surgical procedure is not established. A small series of traumatic distal tendon ruptures was treated surgical in our hospital and was followed up after 12 months concerning their function. Very good and good results could be found with a strong reintegration of the tendon by using transosseus sutures with non resorbable suture material. The refixation with suture anchors showed disappointing results with early pull-outs of the anchor. Revision with screw augmentation with a washer had to be performed. Concerning the biomechanical forces, which show up on the olecranon (up to 40 NM), the refixation of the triceps tendon has proved to be extremely resistant against pull out forces. The good results by using non absorbable transosseus sutures led to a standardized procedure in our trauma center, even the rupture is not traumatic.

Arthroscopic-assisted treatment of a reversed hill-sachs lesion: description of a new technique using cerament.

Purpose. Impaction fractures of the anterior aspect of the humeral head, the reversed Hill-Sachs lesion, are common in posterior shoulder dislocation. We present a new technique to address these lesions arthroscopic-assisted with the use of a bone substitute. Methods. We report the case of a 45-year-old male with a reversed Hill-Sachs lesion after posterior shoulder dislocation. Initially a glenohumeral arthroscopy is performed to address concomitant intra-articular injuries. Guided by the k-wire a cannulated sizer was inserted for reduction of the fracture under arthroscopic visualization. For reduction of the impacted part of the humeral head the subcortical defect was filled with an injectable bone substitute (Cerament) to prevent secondary dislocation. Results. X-ray at follow-up 6 months after the index procedure documents the bony remodeling of the bone substitute. At that time the patient was pain-free (VAS 0) and satisfied with the outcome (Constant score: 78, Rand-36 score: 84, Rowe score: 81) with a good ROM. Conclusions. In conclusion, arthroscopic-assisted reconstruction of reversed Hill-Sachs lesions with an injectable bone substitute is feasible and may provide patients with all the benefits of an anatomic reconstruction with decreased risks related to open surgery.

Treatment of femoral neck fracture with a minimal invasive surgical approach for hemiarthroplasty - clinical and radiological results in 180 geriatric patients.

PURPOSE: The Direct Anterior Approach (DAA) is well established as a minimal access approach in elective orthopaedic hip surgery. For the growing number of elderly patients with femoral neck fractures treated with Bipolar Hip Hemiarthroplasty (BHH), only a few results do exist. The study shows the clinical and radiological outcome for 180 patients treated by a modified DAA with BHH. MATERIALS AND METHODS: The data of 180 geriatric patients with medial femoral neck fractures were evaluated retrospectively. The general and surgical complications, mobilisation using the Timed Up and Go test (TUG), the social environment pre- and postoperative and the radiological results have been compared with established approaches for geriatric hip surgery. RESULTS: After joint replacement, 18 (10%) patients were developed pneumonia, of which 3 (1.7%) died during hospitalisation. In 7 cases (4%), surgical revision had to be carried out: three times (1.7%) because of a seroma, three times (1.7%) because of subcutaneous infection, and one time (0.6%) because the BHH was removed, owing to deep wound infection. One dislocation (0.6%) occurred, as well as one femoral nerve lesion (0.6%) occured. 88.3% of patients were mobilised on walkers or crutches; the Timed Up and Go Test showed a significant improvement during inpatient rehabilitation. 83% were discharged to their usual social environment, 10% were transferred to a short-term care facility and 7% were relocated permanently to a nursing home. 3/4 of patients had a cemented stem alignment in the range between -5° and 5°, while 2/3 of patients had a maximum difference of 1 cm in leg length. CONCLUSION: Using the modified DAA, a high patient satisfaction is achieved after implantation of a BHH. The rate of major complications is just as low as in conventional approaches, and rapid mobilisation is possible.

An economic analysis of aseptic revision hip arthroplasty: calculation of partial hospital costs in relation to reimbursement.

INTRODUCTION: Aseptic loosening is one of the most common intermediate and long-term complications after total hip replacement (THR). These complications cause suffering and require expensive revision surgery. Little concrete data on direct costs are available from the hospital's, moreover operating department's perspective. We here provide a detailed analysis of the costs of THR revision and relate them to reimbursement underlying the German diagnosis-related groups (DRG) system. MATERIALS AND METHODS: Major cost parameters were identified using for orientation the cost matrix of the German Institute for Hospital Reimbursement (InEK GmbH). We then retrospectively analysed the major direct costs of aseptic revision THR in terms of contribution margins I and II. The analysis included a total of 114 patients who underwent aseptic revision from 1 January 2009 to 31 March 2012. Data were retrieved from the hospital information system and patient records. All costs of surgery, diagnostic tests, and other treatments were calculated as purchase prices in EUR. The comparative analysis of direct costs and reimbursements was done for DRG I46A and I46B from the hospital's, especially treating department's rather than the society or healthcare insurance's perspective. RESULTS: The average direct cost incurred by the hospital for a THR revision was 4,380.0. The largest share was accounted for surgical costs (62.7 % of total). Implant and staff costs were identified as the most important factors that can be influenced. The proportion of the daily contribution margin that was left to cover the hospital's indirect cost decreased with the relative cost weight of the DRG to which a patient was assigned. CONCLUSION: Our study for the first time provides a detailed analysis of the major direct case costs of THR revision for aseptic loosening from the provider's perspective. Our findings suggest that these revision operations could be performed cost-beneficially by the operating unit. From an economic perspective, cases with higher cost weights are more favorable for a hospital. These results need to be confirmed in multicenter studies.

[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.

Modified direct anterior approach in minimally invasive hip hemiarthroplasty in a geriatric population: a feasibility study and description of the technique.

INTRODUCTION: The direct anterior approach (DAA) is generally accepted method for minimal invasive arthroplasty of the hip. As good results for total hip arthroplasty are already published, there is a lack of evidence for the implantation of bipolar hip hemiarthroplasty (BHH) in elderly patients with osteoporosis after femoral neck fracture. MATERIALS AND METHODS: For hip arthroplasty using a direct anterior approach (DAA) in elderly patients with femoral neck fractures, a number of modifications of the original technique are being described. The modified DAA considers in particular the co-morbidity and the bone quality of the geriatric patient population. A consecutive series of 16 hemiarthroplasties using this technique is presented. In all 16 cases, the BHH was implanted in modified DAA technique. Mobility measured by 4-item Barthel Index, pain via visual analogue scale (VAS), duration of surgery, external length of incision and blood loss were evaluated. RESULTS: There was no major operative complication during the procedures. The pain level decreased from 7 (preoperatively) to 0 at postoperative day 40. The Barthel Index increased from 5 at first postoperative day to 40 at day 40. Early postoperative mobilisation is efficiently accelerated. Mean operating time was 71 min; the medium skin incision length was 8 cm. The mean haemoglobin level decreased from 118 g/dl preoperatively to 101 g/dl at first postoperative day. CONCLUSION: The described modifications of the DAA help to implant a BHH gently in elderly patients with increasing risk of complications like iatrogenic fractures, wound or prosthesis infections and haematoma. This will hopefully lead to a faster rehabilitation and lower mortality rate for patients with femoral neck fractures in the future.

Midterm Results of 58 Fractures of the Coronoid Process of the Ulna and their Concomitant Injuries.

BACKGROUND: In general, fractures of the coronoid process are rare and usually occur in combination with additional elbow joint injuries. The treatment of these injuries aims to regain a stable as well as a flexible and loadable joint. Although there is currently little evidence, therapy recommendations remain controversial. Therefore, the aim of this study was to prognostically determine relevant factors for therapy recommendation by analysing a representative patient population of two trans-regional trauma centres. MATERIAL AND METHODS: Seventy-seven patients with a fracture of the coronoid process were treated within an 8-year period (2001 to 2009). After an average of 48 months (SD 31), treatment outcome of 58 patients (75%) was acquired. The results were statistically analysed. RESULTS: The average age of the patient was 51.8 years (SD 13.6); 36 were male and 34 had a fracture on the right arm. Applying the fracture types of the coronoid process in accordance with Regan/Morrey, the result was: Type I (19), II (17) and III (22). Further injuries were also detected: 40 radial head fractures, 17 proximal ulnar fractures and 2 fractures of the olecranon. A luxation was detected in 44 of the 58 patients (76%). The patients' average MEPS (Mayo Elbow Performance Score) was 80.6 points (SD 18), with significant differences between the various therapy strategies. Fifteen% of the coronoid process fractures were reconstructable to a limited extent only by means of osteosynthesis. In 33% of the patients, instabilities remained. The average extension/flexion came to 107° (SD 28), and pronation and supination 153° (SD 38). CONCLUSION: At present, a surgical therapy of ligamentary injuries cannot be statistically justified. A stable osseous reconstruction appears to make more sense. The strongest negative prognostic parameters in our patient population were: therapy with an external fixator, immobilisation for more than 21 days, the occurrence of complications and unstable osteosyntheses on the coronoid process.

[Intermediate and long-term outcome after total joint replacement for hallux rigidus : a retrospective analysis]. / Mittel- und langfristige Ergebnisse nach endoprothetischer Versorgung des Hallux rigidus : Eine retrospektive Analyse.

BACKGROUND: The treatment options for advanced hallux rigidus include arthrodesis, excision arthroplasty (Keller-Brandes) and joint arthroplasty and based on the literature, arthrodesis still appears to be the gold standard. In recent years, technical advances and higher patient demands have led to an increasing use of total joint replacement but comparative data on patient satisfaction and clinical outcome of different forms of treatment are rare. MATERIAL AND METHODS: Between 1995 and 2005 a total of 27 patients were treated with 28 joint replacements of the first metatarsophalangeal joint (MTPJ) in a surgical practice (Bio-Action Great Toe Implant, OsteoMed, Addison, TX). The mean age of the patients was 63.7 years. In a retrospective analysis patients were examined clinically and radiologically after a mean follow-up period of 8.8 years and asked about their satisfaction with surgical results using a questionnaire. RESULTS: After joint replacement 15 patients (53.6%) were free of pain, 8 (28.6%) reported marked improvement, 12 (42.9%) had no limitations in any activity and another 5 (17.9%) had no restrictions in activities of daily life. The maximum walking distance was improved in 21 patients (75%) and walking on rough ground in 24 (85.7%). Of the patients 11 (39.3%) had a good range of motion in the MTPJ, 13 (46.4%) reported a slight restriction, 24 (85.7%) were satisfied or very satisfied with the postoperative result and 22 stated that they would undergo joint replacement again. The results of the Wilcoxon test showed a significant increase in postoperative modified American Orthopaedic Foot and Ankle Society (AOFAS) scores compared with preoperative scores. There was loosening of the phalangeal component in 3 patients (11%), and 2 had to undergo revision. CONCLUSIONS: Many recent studies reported good to excellent long-term results of arthrodesis of the MTPJ for stage III and IV hallux rigidus. The results of this study suggest that similar results can be achieved by an experienced foot surgeon with total joint replacement in strictly selected patients.

Refixation of osteochondral fractures by ultrasound-activated, resorbable pins: An ovine in vivo study.

OBJECTIVES: Osteochondral injuries, if not treated adequately, often lead to severe osteoarthritis. Possible treatment options include refixation of the fragment or replacement therapies such as Pridie drilling, microfracture or osteochondral grafts, all of which have certain disadvantages. Only refixation of the fragment can produce a smooth and resilient joint surface. The aim of this study was the evaluation of an ultrasound-activated bioresorbable pin for the refixation of osteochondral fragments under physiological conditions. METHODS: In 16 Merino sheep, specific osteochondral fragments of the medial femoral condyle were produced and refixed with one of conventional bioresorbable pins, titanium screws or ultrasound-activated pins. Macro- and microscopic scoring was undertaken after three months. RESULTS: The healing ratio with ultrasound-activated pins was higher than with conventional pins. No negative heat effect on cartilage has been shown. CONCLUSION: As the material is bioresorbable, no further surgery is required to remove the implant. MRI imaging is not compromised, as it is with implanted screws. The use of bioresorbable pins using ultrasound is a promising technology for the refixation of osteochondral fractures.

[Medical appraisal of anterior cruciate ligament ruptures]. / Begutachtung der vorderen Kreuzbandruptur.

BACKGROUND: Anterior cruciate ligament tears are one of the most common human ligament ruptures. The assessment of such ruptures is particularly difficult because most ACL injuries involve minimal to no contact. The steps of the assessment are presented with the necessary requirements. METHOD: Criteria for determining the cause of anterior cruciate ligament ruptures are discussed against the background of our experience and the literature. Different definitions of causality apply to German statutory accident insurance (workers' compensation) on the one hand and to private accident insurance on the other. RESULTS: The assessment of disability within the scope of workers' compensation in most cases results in "under 10 to 30%", while in private accident insurance it is rated as 1/10 to 1/20 degree of disablement.

[Sledge versus bicondylar surface treatment in the endoprosthetic therapy for unicompartmental knee arthrtitis--a comparative cost analysis]. / Kostenvergleichskalkulation der Schlitten- vs. bikondylären Oberflächenversorgung am Kniegelenk.

BACKGROUND: The G-DRG system reimburses sledge endoprosthetic implantations (UKA) at a much lower rate than surface replacements (TKA), at significantly different cost weights (CW). Therefore, when only G-DRG payments are considered, the complete endoprosthesis implantation produces higher gains. An orientation on these revenues alone, however, does not provide the basis for an economically sound decision-making process. The aim of this study is to present a comparison of the variable costs of the two procedures. MATERIAL AND METHODS: The mean cost and performance data of 28 Endo-Model UKA implantations and of 85 NexGen CR TKA replacements were compared with each other in 2007. RESULTS: From the perspective of the hospital, when the correct medical indication is present, UKA treatment is of greater economic advantage. In this way the total unit contribution margin can be improved, and although the relative weighting is comparatively low, the costs are significantly lower than in a comparative analysis of the TKA. CONCLUSION: For the desired maximisation of the unit contribution margin, assuming that it is the proper medical indication, the recommendation for the hospital would be implantation of the UKA. Considered from the economic perspective of gains and costs, the assumption that a TKA would be advantageous could not be confirmed in the present study.