[Metaphyseal fitting short-stem prosthesis - preliminary results of a prospective single-surgeon series]. / Metaphysär verankernde, zementfreie Kurzschaftprothese - klinisch-radiologische Ergebnisse einer prospektiven Single-Surgeon-Studie.

BACKGROUND: Conventional uncemented femoral stems provide good long-term fixation in patients with a wide range of clinical function. However, preservation of bone stock, and minimally invasive approaches have led to exploration into various other implant designs. Short-stem prosthesis focusing on a stable metaphyseal fit have emerged to address these challenges in total hip arthroplasty. The purpose of this study was to evaluate the clinical and radiological results of a newly developed short-stem hip prosthesis AIDA® in context of a single surgeon study. MATERIAL AND METHODS: From February 2009 to December 2013, 72 cementless "AIDA® short stems" (Fa. Implantcast) were implanted by a single surgeon in one study centre via the Watson Jones interval. All patients signed informed consent prior to screening and the study design was approved by the local ethics committee. 51 patients with 52 implants (35 female, 36 male) with a follow-up > 24 months were included in this prospective, controlled clinical trial. The patients were pre- and postoperatively examined clinically and radiological by a specified protocol. RESULTS: The average patient age at the time of THA was 61 ± 3.2 years (min.-max. 46-68 years). At the last follow-up, the average Harris Hip score increased from 41.4 ± 4.5 preoperatively to 96.8 ± 3.2 points postoperatively. The hospital stay was 9.1 days on average. The X-rays showed in all cases a stable fixation of the stems with full bony integration and no signs of loosening or migration. There were no specific complications relating to the less invasive approach. Postoperatively one periprosthetic fracture was evident. The revision operation into a cementless stem was done without any complications (revisions rate 1.9 %). CONCLUSION: The newly developed "AIDA short stem" is a promising hip implant for the young and active patient with osteoarthritis of the hip. The short-term results are encouraging, but nevertheless mid- and long-term results must be further observed on a prospective basis as part of this collective study.

Cell-free repair of small cartilage defects in the Goettinger minipig: which defect size is possible?

PURPOSE: Cartilage repair of full-thickness chondral defects in the knees of Goettinger minipigs was assessed by treatment with cell-free collagen type-I gel plugs of three different sizes. METHODS: In 6 adult Goettinger minipigs, three full-thickness chondral defects were created in the trochlear groove of one knee of the hind leg. These defects were treated with a cell-free collagen type-I gel plug of 8, 10, or 12 mm diameter. All animals were allowed unlimited weight bearing. After 1 year, the animals were killed. Immediately after recovery, a non-destructive biomechanical testing was performed. The repair tissue quality was evaluated immunohistologically, collagen type-II protein was quantified, and a semiquantitative score (O'Driscoll score) was calculated. RESULTS: After 1 year, a high number of cells migrated into the initially cell-free collagen gel plugs and a hyaline-like repair tissue had been created. The O'Driscoll scores were: 8 mm, 21.2 (SD, 2.8); 10 mm, 21.5 (SD, 1.6); and 12 mm, 22.3 (SD, 1.0). The determination of the e-modulus, creep and relaxation revealed that mechanical properties of the two smaller defects were closer to unaffected hyaline cartilage. CONCLUSIONS: As cell-free collagen type-I gel plugs of all three different sizes created hyaline-like repair tissue, this system seems suitable for the treatment of even larger defects.

[Clinical and gait analytical investigation of valgus knee bracing in therapy for medial degenerative joint disease of the knee]. / Klinische und ganganalytische Untersuchung einer valgisierenden Kniegelenkentlastungsorthese in der Therapie der medialen Gonarthrose.

GOALS: The non-operative treatment of medial degenerative joint disease of the knee has proven to be difficult due to the underlying deformity and the pathological mechanical loading. Valgus knee bracing offers the possibility to directly address the mechanical deficit. The aim of this study was to analyse whether or not part-time valgus knee bracing in patients with medial osteoarthrits can effectively reduce knee pain and lead to reproducible changes in the gait analysis in comparison to an elastic knee bandage and an untreated control group. MATERIAL AND METHODS: In a prospective trial, 33 patients with symptomatic medial osteoarthritis of the knee joint with a minimum of grade 2 according to the radiographic classification of Kellegren & Lawrence were randomised into a treatment group with a valgus brace (n = 13; M4 OA®, Medi) and an elastic knee bandage (n = 10; Genumedi®, Medi). Both supportive devices were to be applied for 2-4 hours per day, especially during activity. The control group (n = 10) consisted of untreated individuals. The deviation of the leg axis and the degree of degenerative joint disease were evaluated radiographically at the onset of the study by a standing whole leg X-ray. The evaluation at the beginning of the study and after 16 weeks consisted of a clinical examination including various knee scores (Insall score, Lequesne score, HSS score, Tegner score, WOMAC, and VAS for pain). Additionally, at both times a 3-dimensional, instrumented gait analysis was carried out to document the joint angles of the affected knee in all planes. The obtained knee joint angles from all groups at both time points were compared to a control group of healthy persons without a history of knee pain by qualitative measurement. RESULTS: Radiographically, the medial deviation of the load axis from the knee joint centre (MAD) was 29 mm. In 27 patients we found a combination of femoral, intra-articular and tibial changes contributing to the varus alignment. The joint line conversion angle (JLCA) was pathological in all subjects. Clinically, in 4 of 5 subjective and objective scores (Insall score, Lequesne score, Tegner score, WOMAC, and VAS for pain) a statistically significant improvement of the symptoms, joint function and activity level thanks to the application of the corrective valgus knee brace was documented after 16 weeks. The knee bandage also led to an improvement, but only in 2 scores (Insall score, Tegner score). No changes were documented for the control group. The gait analysis of the orthosis group revealed an improvement in the extension and flexion angles (sagittal plane) and the knee rotation angles (horizontal plane) when compared to a control group. CONCLUSION: The correction obtained by this knee orthosis, which places a valgus stress on the medially osteoarthritic knee, is an effective addition to the conservative treatment protocols and is superior to the isolated use of an elastic knee bandage. Further research is warranted to evaluate the longevity of such treatment and to further improve the technique of gait analysis by the development of quantitative parameters.

[Tissue engineering of cartilage replacement material - mechanical stimulation in the in-vitro cultivation of human chondrocytes]. / Tissue Engineering von Knorpelersatzgewebe - Mechanische Stimulation in der In-vitro-Kultivierung von humanen Chondrozyten.

The treatment of cartilage defects remains a major problem in orthopaedics. With regard to cartilage tissue engineering, the reimplantation of pre-cultivated chondrocytes in the form of a chondrocyte graft is a promising alternative to conventional methods. Clinical practice requires this MACT procedure (matrix-associated autologous chondrocyte transplantation) to produce a biocompatible replacement tissue with adequate mechanical properties. Mechanical stimulation has the capacity to improve the quality of these cell-seeded biomaterials. By altering chondrocytes' cellular activities, the biological and biomechanical properties of cartilage replacement tissue can be modulated. Different systems are used for this purpose, e.g. shear, perfusion, hydrostatic pressure or compression. The mechanisms, biological effects, chances and problems of the techniques are presented and assessed. Among the stimulating techniques considered are systems that apply indirect and direct shear forces such as spinner flasks, rotating-wall bioreactors, direct tissue shear and perfusion culture systems. The application of hydrostatic pressure or compression may be brought about by either static or dynamic loading systems. Compressive loading is considered in the light of both its short- and long-term effects; additionally two exemplified systems are discussed in detail. However, despite promising approaches and seemingly favourable tissue characteristics, the in vitro culturing of functional cartilage replacement tissue with cartilage-like mechanical and biological characteristics still remains elusive. Furthermore, controlling, monitoring and regulating culturing conditions are general biotechnological requirements of a standardised in vitro cultivation. Among these, different aspects such as aseptic operation, media supplementation, nutrient and gas exchange, temperature and humidity control are considered.

[Muscle strength of the cervical and lumbar spine in triathletes]. / Das muskuläre Profil der Halswirbelsäule und der Lendenwirbelsäule bei Langstreckentriathleten.

AIM: The goal of this study was to analyse the muscle strength of the cervical and lumbar spine in ironman triathletes. The values were compared to the results obtained from a reference group. The test of the triathletes was carried out in an attempt to define a specific strength profile for these athletes. METHOD: In this study, 20 long-distance triathletes (∅ 37.3 ± 7.6 years of age, ∅ 1.80 ± 0.1 m, ∅ 73.7 ± 6.0 kg) were evaluated with regard to their individual and sport-specific strengths of the cervical spine in 2 planes and of the trunk strengths in all 3 planes of motion. The trunk strength profile of the triathletes revealed good average results in the trunk extensors and the lateral flexors of the left trunk. The reference group is the data base of the company Proxomed®, Alzenau. It is based on results of 1045 untrained, symptom-free subjects of different ages. RESULTS: Lumbar extension: The extension of the force values shows no significant difference from the reference group. Lumbar flexion: The flexion tests show highly significantly lower force values (5.025 ± 0.81 N/kg vs. 6.67 ± 0.6 N/kg) than the reference group. Flexion/extension: In the sagittal plane values for the triathletes demonstrate an imbalance in muscle strength ratios. The abdominal muscles turn in relation to the back extensor muscles too weakly to be very significant. Lumbar rotation: The force values of the athletes in both directions (right: 6.185 ± 1.46 N/kg, left: 7.1 ± 1.57 N/kg vs. 10.05 ± 0.34 N/kg) are highly significantly (p ≤ 0.001) lower than the reference values. Ratio of rotation left/right: The ratio of left/right rotation in the reference group is set at 1 and thus shows an equally strong force level between the two sides. Lumbar lateral flexion: The triathletes do not show any significant differences between the force values. Compared to the reference group there is no significant difference to the left side flexion. In the lateral bending the athletes have significantly better values than the reference group. Ratio of lateral left/right: In the reference group the ratio is set at 1. For triathletes, it shows an average value of 0.93. This difference is not significant. Cervical extension: The extension of the force values (1.96 ± 0.59 N/kg vs. 3.03 ± 0.24 N/kg) shows a highly significant difference from the reference group. Cervical flexion: In flexion (1.3 ± 0.42 N/kg vs. 2.17 ± 0.22 N/kg) triathletes have highly significantly lower strength values than the reference group. Flexion/extension: The triathletes did not differ significantly from the reference values (0.69 ± 0.23 and 0.72 ± 0.08). Lateral cervical spine: In comparison to the reference group (left: 1.67 ± 0.48 N/kg, right: 1.55 ± 0.46 N/kg vs. 2.36 ± 0.15 N/kg) in which there is left/right lateral flexion, there is a highly significant difference. Right lateral flexion is weaker than the left. Ratio of lateral left/right: The triathletes have a significant imbalance in the lateral flexion of the cervical spine compared to the reference group (1.07 ± 0.15 to 1). CONCLUSION: In conclusion, in the triathlon there is a specific stress that is obviously not an adequate stimulus for the muscles of the cervical spine in order to achieve a balanced musculature and the athletes should be advised to practice a preventive approach with regard to these areas.

[Comparison of trunk muscle strength of soccer players with and without low back pain]. / Vergleich der Rumpfmuskelkraft von Fussballspielern mit und ohne Rückenschmerzen.

AIM OF THE STUDY: Low back pain in soccer players is one of the frequently appearing disorders caused by overuse. Myogenic dysbalances are under discussion as possible reason for this problem. In the present study the muscular strength profile of the trunk musculature of soccer players with and without low back pain was evaluated. The results of the asymptomatic players were compared to those of players with low back pain; furthermore, the collected data were compared to those of an asymptomatic reference group. The question posed was whether soccer players show a specific strength profile caused by the special, sports-specific requirements and whether this strength profile differs between players with and without low back pain. METHOD: In the present study the isometric maximal strength of 18 soccer players with and 18 soccer players without low back pain was measured in all 3 planes. The reference group was provided by the Proxomed company, which had previously analysed 1045 healthy untrained individuals of various age groups. RESULTS: The soccer players showed a sport-specific profile for the musculature, which was determined by a significant reduction of the flexion and rotation strength (flex: Ø 5.21 N/kg vs. Ø 6.49 N/kg; Ø 5.78 N/kg vs. Ø 6.66 N/kg respectively; rotation: left 7.09 N/kg, right 8.69 N/kg vs. left/right 10.1 N/kg; left 7.22 N/kg, right 8.24 N/kg vs. left/right 10.0 N/kg, respectively) as well as by an increased lateral flexion strength to the right-hand side in comparison to the reference group (lat. flex. right: 9.87 N/kg, respectively, 10.67 N/kg vs. 8.3 N/kg). A statistically significant correlation between the muscular activity in the trunk stability of soccer players with and without low back pain could not be shown. CONCLUSION: Obviously sports-specific training with additional specific training of the trunk muscles is not sufficient for the development of a balanced strength of trunk musculature. In the present study an influence of the performance of the trunk musculature on the incidence of low back pain could not be shown.

[Perioperative management in outpatient arthroscopy of the knee joint]. / Perioperatives Management in der ambulanten arthroskopischen Chirurgie des Kniegelenks.

AIM: Nowadays, complex arthroscopic procedures of the knee joint, such as ACL reconstruction, are routinely carried out on an outpatient basis. The reduced time spent with the patient places high demands on the surgeon with regard to the management of such cases. The aim of this study was to evaluate the current standards of perioperative management following outpatient arthroscopic surgery of the knee in Germany. METHODS: A questionnaire consisting of 18 questions was sent to 215 members of the German Association of Outpatient Arthroscopy (BVASK e. V.), dealing with the following topics: antibiotic prophylaxis, DVT prophylaxis, use of a tourniquet and suction drain, physical therapy, physiotherapy, analgesia, anaesthesia and emergency management. More than 51% of the forms were returned and considered suitable for statistical analysis. RESULTS: A total of 62% of the surgeons reported the use of an antibiotic prophylaxis (i. v. single shot) in every arthroscopic case, while 19% administer antibiotics only occasionally, especially in ACL reconstruction. Postoperative antibiotic treatment was reserved for special situations, such as prior joint infection. Prophylaxis of DVT by means of low molecular weight heparin was carried out in 96% of the cases. 51% prescribed anticoagulant agents for 1 week, 39% for the duration of reduced weight bearing. Half of the surgeons used a tourniquet cuff, 22% exsanguinate the limb prior to cuff inflation. A suction drainage was applied by 36% of the surgeons regularly and by 45% occasionally. The drain is left for one day by 79% of the surgeons, while 11% reported a shortened use of only several hours. With regard to analgesia, 66% of all surgeons apply some kind of local anaesthetic into the knee joint post surgery. Systemic preoperative analgesics or anti-inflammatory agents are given regularly in 56 % of the cases. A total of 92% of the procedures are carried out under general anaesthesia. In 36% of the cases, some kind of additional regional peripheral anaesthesia is used. With regard to postoperative care, cryotherapy is considered standard (97%) and 64% of the surgeons recommend physiotherapy. Nearly all surgeons (97%) offer the patients the opportunity to reach them personally via mobile phone during the first night following arthroscopic surgery. CONCLUSIONS: DVT prophylaxis with LMWH, general anaesthesia, postoperative cryotherapy and personal availability by phone can be considered part of the standard perioperative management following outpatient knee arthroscopy in Germany. However, a wide variety of treatment options can be found regarding topics such as analgesia, antibiotic prophylaxis, tourniquet, knee drainage and physiotherapy.

[Influence of sex and side dominance on the results of quantitative, three-dimensional motion analysis of the upper extremities]. / Einfluss des Geschlechts und der Seitendominanz auf die Ergebnisse der quantitativen, dreidimensionalen Bewegungsanalyse der oberen Extremitäten.

AIM: Clinical assessment does not provide objective and quantitative evaluation of the shoulder function. Based on instrumental gait analysis a system for three-dimensional motion analysis of the upper extremities has been developed. The aim of this study is to evaluate the results of instrumental upper extremity motion analysis with respect to dependence on sex and side dominance. METHOD: 16 healthy subjects (8 male, 8 female, mean age 26 years) were included. Three-dimensional motion analysis was carried out with a video-based system and passive markers. All subjects performed two movement tasks representing activities of daily living (task A: reaching the neck, task B: removing a parking token). All joint angles of the upper extremity were recorded and graphically displayed. Additionally, a calculation of quantitative parameters was performed. RESULTS: Contrary to expectations the task "reaching the neck" was not combined with external shoulder rotation. Females performed most of the tasks quicker and with higher reproduction accuracy. Movement reproduction accuracy was rarely dependent on dominance. CONCLUSION: Three-dimensional upper extremity motion analysis of activities of daily living allows a precise and quantitative evaluation of movement patterns. The differences with respect to sex and side in a healthy group have to be respected in studies dealing with comparative shoulder function.

[Optical coherence tomography (OCT) to evaluate cartilage tissue engineering]. / Die optische Kohärenztomografie (OCT) zur Darstellung der Regenerateigenschaften im Tissue Engineering von Knorpelgewebe.

AIM: The aim of this study was to investigate hyaline cartilage defects treated with cell-seeded artificial matrix systems (two different collagen type I gels) with the method of optical coherence tomography (OCT) and to correlate the results with conventional histological and immunocytochemical staining. METHOD: Osteochondral blocks were harvested from 20 patients undergoing total knee replacement and trimmed to 2 x 2 cm. Under sterile conditions, chondral defects of 8 mm diameter were either filled with a collagen type I gel plug seeded with autologous chondrocytes (2 x 10 (5)/mL gel), or with a corresponding gel plug which was stabilised by a 20-fold compression. Of each group, 5 specimens were cultivated for 6 weeks under standardised in vitro conditions (37 degrees C, 5 % CO (2), humidified atmosphere), while the remaining 5 specimens were implanted subcutaneously in nude mice (BALBc -/-). Immediately after recovery, the repair tissue and bonding zones were investigated by OCT. Subsequently, specimens were decalcified and investigated by H&E staining and collagen type II immunostaining. The results of OCT and conventional staining were correlated. RESULTS: By OCT, repair tissue could be investigated up to 1.6 mm in depth, physically limited by the utilised OCT system. In the denser hyaline cartilage regions, OCT resolution was reduced. Regardless of cultivation (in vitro or nude mouse), ultrastructural features of the repair tissue could be demonstrated. In particular, ultrastructural differences between the two investigated collagen gels could be detected. Moreover, the bonding region between repair tissue and hyaline cartilage could be evaluated by OCT investigation. The results of the OCT measurements were confirmed by H&E and collagen type II immunostaining. CONCLUSION: By OCT, repair tissue generated by the treatment of cartilage defects with tissue-engineered matrix systems could be evaluated in vitro. Future studies may show if repair tissue quality may be monitored in situ by OCT.

[Functionality and accuracy of a fluoroscopic navigation system in the placement of the femoral component for hip resurfacing - a cadaver study]. / Funktionalität und Genauigkeit eines fluoroskopischen Navigationssystems zur Implantation von Hüftkopf-Oberflächenersatzprothesen: Eine Anatomiestudie.

INTRODUCTION: Resurfacing arthroplasty represents an alternative method to total hip replacement especially for the young and active patient. The main reasons for early implant failure are mal-positioning of the femoral component and notching of the femoral neck during femoral head preparation. MATERIAL AND METHODS: In the context of a cadaver study of formalin-fixed cadaveric full body specimens 6 DUROM -Hip-Resurfacing prosthesis have been implanted under navigation control. The aim of the study was an evaluation of the functionality and accuracy of the computer-assisted planning and navigation system on the basis of a navigation module library from Surgitaix AG Aachen, Germany. RESULTS: The main angulation error between planning (135.2 +/- 3.6 degrees ) and navigation (136.2 +/- 2.8 degrees ) was 1.9 +/- 1.1 degrees , the main anterior offset error between planning (2.2 +/- 1.3 mm) and navigation (2.7 +/- 2.3 mm) was 1.2 +/- 1.9 mm. The main distance error between planning and navigation was 2.7 +/- 1.3 mm. The mean time for all five planning and navigation steps was 20.2 +/- 2.5 min. Against the background of a acetabular bone-saving approach in all 6 cases the smallest possible femoral component could be implanted. CONCLUSION: The computer-assisted fluoroscopic planning and navigation system for hip resurfacing showed within the scope of this cadaver study first promising results. The system approaches a practicable intraoperative planning with a high accuracy in operative implementation. Nevertheless, the potential benefit has to be evaluated in further clinical studies, especially from the perspective of a possible integration of this navigation system into the clinical work-flow. Further studies should consider a fluoroscopic-assisted range of motion assessment under consideration of an additional cup-module to enhance the postoperative range of motion after hip resurfacing procedures.

[Clinical results after three years use of matrix-associated ACT for the treatment of osteochondral defects of the knee]. / Klinische Drei-Jahres-Ergebnisse der matrixgekoppelten ACT zur Behandlung osteochondraler Defekte am Kniegelenk.

AIM: The aim of this study was to examine the clinical results after the treatment of osteochondral defects of the knee with autologous bone grafting and matrix-supported autologous chondrocyte transplantation (ACT). METHOD: In this study 13 patients with osteochondral defects of the knee (12 femoral, 1 tibial) with OCD ICRS grade IV or ICRS grade IV B were included. The osteochondral defects were reconstructed simultaneously with autologous monocortical cancellous bone cylinders or chips from cancellous bone and matrix-supported autologous chondrocyte transplantation (CaReS). Data were analysed in accordance with the ICRS criteria and the Brittberg score. Patients were followed up to 36 months after the operation. RESULTS: The average age of the patients was 34.9 (16 - 47) years at the time of surgery. The size of the defect was 8.1 (3.8 - 13.5) cm(2). The subjective and objective IKDC scores, the Brittberg and the ICRS function score were statistically significantly improved during the observation time. In one patient the transplantation failed and another patient was not available for the follow-up at 36 months. The objective IKDC score and the ICRS function score increased from 0/13 (0 %) to 11/12 (91.7 %) in categories A and B, or I and II, respectively, after 3 years. At this point of time 83.4 % (10/12) of the patients voted the treatment as excellent or good. The subjective IKDC score improved from 38.4 (+/- 12.7) preoperatively to 66.1 (+/- 17.0) after 3 years. CONCLUSION: The treatment of osteochondral defects of the knee with autologous bone grafting and matrix-supported autologous chondrocyte transplantation shows promising results even for larger defects. But for a final decision about this therapy the present sample size was too small. There is a need for further long-term investigation with a larger number of patients.

[Mechanical bending strength of explanted ex vivo bone cements compared with in vitro samples]. / Mechanische Biegefestigkeiten von explantierten Ex-vivo-Knochenzementen verglichen mit In-vitro-Proben.

INTRODUCTION: The mechanical properties of acrylic bone cements are an important factor in determining an efficient load transmission between prosthesis and bone to guarantee the long-term stability in cemented hip arthroplasty. MATERIAL AND METHODS: Palacos and Refobacin Palacos specimens from 21 aseptically loosened femoral compoments of cemented hip arthroplasties manufactured by the first to third generation cementing technique have been mechanically tested in a standardised four-point bending test (ISO 5833). In vitro manufactured Palacos and Refobacin Palacos specimens served as a control group. The fatigue fracture surfaces were morphologically analysed with light microscopy. RESULTS: Under in vitro conditions manufactured specimens had higher values of bending strength, with the exception of blood contaminated ones, compared to ex vivo specimens. Ex vivo specimens of the second and third generation cementing technique had higher values than specimens of the first generation. CONCLUSIONS: Acrylic bone cements are subjected to a multifactorial material fatigue in vivo. Here, the art and quality of cementing technique is of eminent importance in determining the long-term stability of cemented hip arthroplasty.

[Surface pretreatment of endoprostheses by silica/silane to optimise the hydrolytic stability between bone cement and metal. Total hip and knee arthroplasty]. / Silikatisierte/silanisierte Implantatoberflächen zur optimierten hydrolysestabilen Verbundfestigkeit zwischen Knochenzement und Metall. Zementierte Hüft- und Knieendoprothetik.

BACKGROUND: The aseptic loosening of cemented total hip and knee arthroplasties is still an unsolved problem. In this regard, the hydrolytic resistance in the metal-to-bone cement interface is of major importance. METHODS: Cemented pretreated femur stems and tibia components coated by means of a silica/silane interlayer system were dynamically loaded with the help of a hip and knee simulator similar to DIN ISO Norm. After loading, the components were microscopically analysed concerning both debonding in the metal-to-bone cement interface and cement mantle defects. These data were matched with uncoated components. Unloaded coated and uncoated femur and tibia components acted as controls. RESULTS: Compared with uncoated components, the pretreated and coated ones yielded a significant reduction in cement defects as well as of debonding in the metal-to-bone cement interface. CONCLUSION: Using the silica/silane interlayer system for cemented femur and tibia components, hydrolytic debonding in the metal-to-bone cement interface with following cement mantle failure can be reduced. This could help increase the long-term stability of the metal-to-bone cement compound, with decreased aseptic loosening.

Surface coating to improve the metal-cement bonding in cemented femur stems.

INTRODUCTION: Hydrolytic debonding of the metal-cement interface is one of the main reasons for aseptic loosening in cemented hip arthroplasty. MATERIALS AND METHODS: BiContact femur stems (CoCrMo-/TiAl6V4-alloy) were coated by a silica/silane interlayer coating system. The stems were cemented into artificial femurs. The cyclical loading (DIN ISO 7206-4) was performed within a hip-simulator. Uncoated stems (CoCrMo-/TiAl6V4-alloy) were prepared and loaded the same way. After loading, the metal-cement and the bone-cement interfaces were analysed. Unloaded uncoated and unloaded coated BiContact stems served as a control. RESULTS: The coated loaded stems showed a significant reduction in debonding and cement failure (P < or = 0.05). A high correlation was documented between debonding and cement failure (rSpear> or = 0.9). There was no significant difference between CoCrMo- and TiAl6V4-stems (P > or = 0.05). CONCLUSION: The silica/silane coating significantly decreased hydrolytic debonding at the metal-bone cement interface with consecutively less cement failure.

[Correction osteotomies near the knee and navigation: state of the art within the scope of the "OrthoMIT" project for the development of an integrated platform for smart interventional orthopaedic surgery and traumatology]. / Die kniegelenksnahe Korrekturosteotomie und Navigation--eine Standortbestimmung im Rahmen des "OrthoMIT"-Projektes zur Entwicklung einer integrierten Plattform für schonende operative orthopädisch-traumatologische Therapie.

INTRODUCTION: "OrthoMIT--minimal invasive orthopaedic therapy" is a project to develop an integrated platform for less invasive operative procedures in hip, knee and spine surgery, supported by the German Federal Ministry for Education and Research (BMBF). Twenty-seven industrial and clinical partners under the management of the Orthopaedic Department of the University Hospital Aachen (Prof. Dr. F. U. Niethard) intend to develop in 10 subprojects innovative aspects and modules of the "OrthoMIT" system. MATERIALS AND METHODS: Within the project and amongst other procedures, joint-preserving correction osteotomies have been analysed to develop planning and navigation tools on the basis of improved and less invasive surgery. Therefore, the reproducibility and validity of the conventional methods were investigated and compared with the technical possibilities in computer-guided planning and navigated surgery for correction osteotomies of the upper extremities. Clinical needs, necessary innovative aspects and modules were defined out of these consolidated findings and passed on to the industrial partners of the "OrthoMIT" project to develop innovative techniques in the field of planning and navigation. CONCLUSION: The present article reports in a concise way about the essentials of the available current techniques in correction osteotomies of the upper extremities with the main focus being placed on navigation.

[Mechanical in vitro testing of fifteen commercial bone cements based on polymethylmethacrylate]. / Mechanische In-vitro-Prüfung von fünfzehn kommerziellen Knochenzementen auf der Basis von Polymethylmethacrylat.

UNLABELLED: INTRODUCTION The long-term stability in cemented hip arthroplasty depends not only on the mechanical properties of the acrylic bone cements but also on an improvement of cementing techniques. MATERIAL AND METHODS: The bending strengths of 15 commonly used bone cements (CMW 3 Gentamycin; CMW 3; Refobacin Palacos R; Palacos R; Palamed G; Palamed; Cerafixgenta; Cerafix; Duracem; Simplex Tobramycin; Simplex P; Versabond; Sulcem; Sulcem 3 Genta; Copal) have been mechanically tested in a standardised in vitro four-point bending test (ISO 5833). The fatigue fracture surfaces were morphologically analysed with light microscopy. RESULTS: The highest values of bending strength were found in vacuum mixed specimens cured under pressure. The lowest values of strength were seen in with blood contaminated specimens. Fatigue cracks were often initiated from air bubbles or other inclusions such as antibiotics or blood in the bone cement. CONCLUSIONS: The present in vitro study highlights the supposition that the quality of the cementing technique is of eminent importance in determining the long-term stability of cemented hip arthroplasties.

[Minimally invasive approaches to the hip joint for total hip arthroplasty: state of the art within the scope of the "OrthoMIT" project for the development of an integrated platform for smart interventional orthopaedic surgery and traumatology]. / Zugangswege zum Hüftgelenk beim künstlichen Gelenkersatz unter minimalinvasivem Aspekt--eine Standortbestimmung im Rahmen des "OrthoMIT"-Projektes zur Entwicklung einer integrierten Plattform für schonende operative orthopädisch-traumatologische Therapie.

INTRODUCTION: Total hip arthroplasty within the field of minimally invasive surgery (MIS) is discussed controversially in the current literature. Potential advantages of MIS should be minimised soft-tissue trauma and thereby less operative loss of blood as well as postoperative pain, resulting in a faster rehabilitation with reduced hospital stay. METHODS: In this article the different minimally invasive approaches to the hip joint for total hip arthroplasty, including anterior, anterolateral, lateral, posterolateral and medial approaches, are reviewed. Potential advantages and disadvantages as well as published results are discussed against the background of evidence-based medicine. RESULTS: The results available so far on minimally invasive approaches for total hip arthroplasty are almost exclusively extracted from retrospective studies and case series. However, the results of randomised controlled studies in an appreciable number of patients are still lacking. CONCLUSION: Minimally invasive approaches to the hip joint have opened a new era in total hip arthroplasty. The current literature does not allow a final judgment about the advantages of MIS in total hip replacement. So far, increasing complications of MIS are reported in the current literature. Until evidence-based data are available, it is strongly recommended that these techniques should only be applied by experienced surgeons.

[Osteochondral marker proteins in the quantitative evaluation of matrix-based autologous chondrocyte transplantation CaRes]. / Osteochondrale Molekülmarker als quantitative Verlaufsparameter nach matrixgekoppelter autologer Chondrozytentransplantation CaRes.

PURPOSE: In this study we attempt to evaluate whether or not osteochondral markers of the synovial fluid can be helpful in defining objectively the repair process following matrix-based autologous chondrocyte implantation (ACI) CaReS (Cartilage Regeneration System). METHODS: As a part of a clinical prospective pilot study, synovial fluid of 19 patients was examined before, as well as 6, 12, 26, and 52 weeks after matrix-based ACI. A synovial fluid analysis was performed and markers of bone and cartilage metabolism were evaluated. Molecular markers routinely examined included MMP-1, MMP-3, MMP-13, TIMP, hCOMP, PICP und MIA. The levels were referenced to the total protein concentration of the synovial fluid and compared with clinical parameters (IKDC) and magnetic resonance imaging (MRI). RESULTS: With the exception of MMP3 all markers showed a drop of the concentration below preoperative levels at 6 weeks. All marker levels returned to below the preoperative concentration at 26 as well as 52 weeks after surgery. The MIA, MMP-3, PICP, hCOMP and TIMP levels showed significant changes over the period of 52 weeks (p<0.01). Statistically significant correlations between the marker levels and the clinical scores could only be observed at several times of assessment. CONCLUSIONS: Under consideration of missing correlations to clinical parameters (IKDC/MRI) non-specific osteochondral marker proteins of the synovial fluid cannot be used without further scrutiny to document changes in cartilage and osseous metabolism following matrix-supported ACI over the time of 52 weeks objectively. The drop of the concentrations below preoperative levels at 6 weeks can possibly be explained by the reduced traumatization of the joint with the CaRes procedure compared to the classic ACI. Specific markers for cartilage metabolism should be defined to permit a direct and objective comparison of the various conservative and operative methods presently available for the treatment of chondral lesions of the knee joint.

[Soft-tissue management in primary knee arthroplasty: common techniques, navigation and force-sensing devices]. / Weichteilmanagement in der primären Kniegelenkendoprothetik: konventionelle Techniken, Navigation und sensorintegrierte Messsysteme.

Soft-tissue management is essential for the outcome in total knee arthroplasty. In combination with osseous resections and component positioning, correction of the underlying ligamentous dysbalance should yield a stable joint throughout the flexion arc. Different "philosophies" with regard to technique, timing and tactics in ligament balancing are described. So far, surgeons have not been provided with standardised devices that allow the objective measurement of this complex issue. Moreover, knowledge concerning the "ideal" soft-tissue stability following knee arthroplasty is still sparse. As part of the scientific project "OrthoMIT" (minimal invasive orthopaedic therapy) an approach to combine conventional soft-tissue management with navigation and force-sensing devices should be realized technically. The aim is to develop an instrument for the objective measurement of soft-tissue management in scientific and clinical applications.

[Durom hip resurfacing arthroplasty: first clinical experiences with a lateral approach]. / Durom-Hip-Oberflächenersatz am Hüftgelenk: Erste klinische Ergebnisse mit dem lateralen Zugang.

INTRODUCTION: We present the first clinical and radiographic results of the Durom Hip Resurfacing prosthesis with a lateral approach. MATERIALS AND METHODS: 52 patients (n = 59 protheses) with a mean follow-up of 25.4 +/- 10 month were evaluated. Clinical evaluation was done using the Harris hip score (HHS), a modified University of California at Los Angeles (UCLA) Activity Level Scale and the Merle d'Aubigné Score pre- and postoperatively. Radiographic evaluation included the preoperative femoral neck-shaft angle, the pre- and postoperative femoral offset, the postoperative stem-shaft angle as well as postoperative periprosthetic radiolucencies. RESULTS: Within the clinical follow-up the postoperative mean HHS (93 +/- 4.3 vs. 41.2 +/- 7.1 points), the modified UCLA (8.8 +/- 2.8 vs. 4.8 +/- 1.9) as well as the Merle d'Aubigné Score (17.1 +/- 1.7 vs. 7.5 +/- 2.1) indicated a significant improvement (p