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BACKGROUND To examine the risk of injury to the popliteal neurovascular bundle (pNVB) during all-inside repair of the posterior horn of the lateral meniscus (PHLM) using Upright-MRIs. METHODS Upright-MRIs of 61 knees in extension (ext) and 90°-flexion (flex) were included. Distance D from the PHLM to the pNVB was compared between extended and 90°-flexed position, subgroups with/without joint-effusion and evaluated according to demographics. Portal safety was assessed simulating suturing of the PHLM via four arthroscopy portals. Distance d (shortest space from the simulated suturing-device trajectory lines to the pNVB) was compared among portals in increasing distances from the posterior cruciate ligament (PCL). RESULTS D is longer in flex (17.3 ± 6.0 mm) than in ext (11.3 ± 4.2 mm, p

To evaluate subjective and objective clinical and magnetic resonance imaging-based radiologic outcomes after short-term follow-up in patients with focal full-size cartilage lesions of the knee joint treated with all-arthroscopic hydrogel-based autologous chondrocyte transplantation.A retrospective study on patients with isolated focal cartilage defects of the knee joint who were treated with arthroscopically conducted matrix-induced autologous chondrocyte transplantation was performed. Clinical scores were assessed at baseline and final follow-up using the Tegner Score, visual analog scale, the International Knee Documentation Committee, and the 5 subscales of the Knee Injury and Osteoarthritis Outcome Score. Magnetic resonance imaging scans of the treated knee joints were evaluated with the updated MOCART (Magnetic Resonance Observation of Cartilage Repair Tissue) 2.0 scoring system at follow-up.Twenty-nine consecutive patients were included in the study. Mean time to follow-up was 24.9 ± 1.1 months. Average visual analog scale decreased significantly from 6.5 ± 3.1 preoperatively to 2.3 ± 1.6 at follow-up (P.0001). Tegner score increased from 3.1 ± 1.3 to 4.3 ± 1.2 (P.0001) and the International Knee Documentation Committee from 43.8 ± 21.9 to 64.9 ± 18.9 (P.0001). Also, all Knee Injury and Osteoarthritis Outcome Score subscales displayed significant improvements. Patients showed similar improvements of nearly all clinical scores independent of the defect size. Average MOCART2.0 score was 70.0 ± 13.6 and 20 patients scored ≥70 points. All 8 patients with large defects (5 cmIn this small study, injectable matrix-induced autologous chondrocyte transplantation therapy in the knee joint led to favourable clinical and radiologic short-term results with significant improvements in all clinical scores and MOCART2.0 scores, confirming morphologic integrity of the transplanted chondrocytes. Therefore, this minimally invasive procedure represents a promising operative technique for cartilage regeneration, even for large-diameter lesions.IV, therapeutic case series.

Although insufficiency of the anterior cruciate ligament (ACL) is a frequent result of an injury, validated tests are associated with unsatisfying validity. Moreover, some of these tests are not easy to perform and patient's muscular resistance often limits their reliability. Therefore, with this study, we want to design an accurate test to diagnose an ACL insufficiency, which is independent of the assessor's skills and overcome any muscular resistance. Fifty patients with an isolated ACL rupture (group A; age 26.4 years ± 14.9 standard deviation [SD]; female, n = 15) and additional 50 patients with an intact ACL but meniscal lesions (group B; age 45.4 years ± 12.9 SD; female, n = 23) were consecutively included in this study. The integrity of the ACL and the menisci were evaluated by magnetic resonance imaging and verified arthroscopically. Two orthopaedic surgeons performed a pivot shift test, a Lachman's test, and our new “forced active buckling” (FAB)-sign test in all patients. The surgeons were blinded for the pathology of the knee and we randomized the tests for each patient and examiner. The sensitivity, specificity, positive predictive value, negative predictive value, and positive and negative likelihood ratios with confidence intervals were calculated and compared. With a prevalence of 0.5, the FAB-sign test revealed the best overall sensitivity of 0.78 compared with the Lachman's and pivot shift tests of 0.74 and 0.46, respectively. Also, the overall specificity of the FAB-sign test of 0.95 was higher than the Lachman's test of 0.83, however, comparable to the pivot shift test of 0.96. The FAB-sign test demonstrated the best positive and negative predictive values of 0.94 and 0.81. There was no significant difference between the two examiners concerning the accuracy of results in each test (p = 0.83). This study shows that the introduced FAB-sign test can detect an ACL insufficiency more sensitive and more specific compared to the pivot shift and Lachman's tests in the subacute phase. This is a randomized controlled diagnostic study, level 1b.

Patellofemoral instability is a severe problem in young and active patients. This pathology is influenced by ligamentous, bony, and neuromuscular parameters. The reconstruction of the medial patellofemoral ligament (MPFL) evolved to a primary procedure, but combined procedures were more frequently performed in the past years. However, additional operative procedures are associated with increased morbidity and no absolute indication can be identified in the literature. This study is intended to clarify whether addressing only ligamentous influence factors (MPFL) in chronic patellofemoral instability is sufficient to produce good clinical outcomes, or whether other risk factors influence the results negatively and should also be treated at some point. In 52 patients with chronic patellofemoral instability patellar height according to Caton-Deschamps, trochlear dysplasia according to Dejour, the leg axis, the femoral antetorsion, tibial tubercle (TT)–trochlear groove, and TT–posterior cruciate ligament distance were evaluated. All patients were treated with isolated MPFL reconstruction. After a minimum follow-up period of 24 months (24–36 months), the clinical outcome results were calculated using the scoring system according to Lysholm and Tegner. Correlation between clinical outcome scores and anatomic risk factors were calculated. The analysis was performed using a standard statistical software package (JMP version 12, SAS Institute, Cary, NC). The average postoperative Lysholm score increased significantly from 57.23 ± 19.9 to 85.9 ± 17.2 points (p

Anteromedial knee injury with rupture of anterior cruciate ligament (ACL) and concomitant lesion of medial collateral ligament (MCL) is common in athletes. No standardized treatment concept can be found within the literature. This study presents results of a new treatment concept for concomitant MCL lesions in patients with ACL rupture. In this study, 67 recreational athletes with ACL injury and concomitant MCL lesion were treated according to a distinct treatment concept. Patients were classified in six different types of concomitant MCL lesion depending on grade of MCL lesion and presence of anteromedial rotatory instability (AMRI). Final classification and surgical indication were determined 6 weeks posttraumatic. All patients received ACL reconstruction. MCL was treated by surgical or conservative regime due to type of concomitant MCL lesion. International Knee Documentation Committee (IKDC), AMRI, and Lysholm scores were evaluated both preoperatively and after 6 weeks, 16 weeks, 12 months, and 18 months postoperatively. All patients could be uniquely classified and treated according to the introduced treatment concept. AMRI was verifiable in patients with grade II and III MCL lesions. All patients showed good to excellent clinical results at the follow-up examinations. In all 67 patients (100%), the findings were graded as normal or nearly normal according to the IKDC knee examination form. Lysholm score averaged 93.9 at final follow-up. The introduced treatment concept showed good results on short-term outcome and provides a sufficient treatment strategy for concomitant MCL lesions in athletes with ACL rupture.

Objective The etiology of osteochondritis dissecans (OCD) is still uncertain. Recently, it has been hypothesized that instability of the anterior horn of the meniscus is an important cause for the development of a nontraumatic OCD in adolescents with good results after surgical stabilization. This case series aims to evaluate the treatment results after meniscus stabilization in adults with nontraumatic OCD. Design Ten patients with magnetic resonance imaging (MRI)-confirmed OCD of the knee joint, meniscal instability, and closed epiphyseal plates were enrolled in this study. The instable meniscus was stabilized by direct suturing of the anterior horn of the meniscus. MRI examinations were performed preoperative and 6 and 12 months postoperative. The OCD was classified arthroscopically according to Guhl and according to Hughes in the MRI. The overall knee function was evaluated by the Lysholm score before treatment and 12 months postoperative. Results Four women and 6 men with a mean age of 20.6 ± 1.9 years were included in this study. Preoperatively 60% of the patients showed a grade II or III lesion arthroscopically and 70% a grade III or IVa lesion in the MRI examination. After arthroscopic meniscus stabilization the Lysholm score increased in average from 48.1 ± 14.12 before treatment to 97.5 ± 3.1 postoperative. At final follow-up after 12 months, an improvement of the OCD in the MRI could be demonstrated in all patients (100%). In 80% of the patients a complete healing of the OCD could be noted. Conclusion The clinical concept of an instable anterior horn of the meniscus as a cause for the development of a nontraumatic OCD seems to be transferable to adults and arthroscopic stabilization can lead to a sufficient healing of this knee pathology.

A common method to derive both qualitative and quantitative data to evaluate osseointegration of implants is histomorphometry. The present study describes a new image reconstruction algorithm comparing the results of bone-to-implant contact (BIC) evaluated by means ofµCT with histomorphometry data. Custom-made conical titanium alloyed (Ti6Al4V) implants were inserted in the distal tibial bone of female Sprague-Dawley rats. Different surface configurations were examined: Ti6Al4V implants with plasma-polymerized allylamine (PPAAm) coating and plasma-polymerized ethylenediamine (PPEDA) coating as well as implants without surface coating. After six weeks postoperatively, tibiae were explanted and BIC was determined byµCT (3D) and afterwards by histomorphometry (2D). In comparison to uncoated Ti6Al4V implants demonstrating low BIC of 32.4% (histomorphometry) and 51.3% (µCT), PPAAm and PPEDA coated implants showed a nonsignificant increase in BIC (histomorphometry: 45.7% and 53.5% andµCT: 51.8% and 62.0%, resp.). Mean BIC calculated byµCT was higher for all surface configurations compared to BIC detected by histomorphometry. Overall, a high correlation coefficient of 0.70 (p<0.002) was found between 3D and 2D quantification of BIC. TheμCT analysis seems to be suitable as a nondestructive and accurate 3D imaging method for the evaluation of the bone-implant interface.

Implant osseointegration can currently only be assessed reliably post mortem. A novel method that relies on the principle of acoustic sound analysis was developed to enable examination of the longitudinal progress of osseointegration. The method is based on a magnetic sphere inside a hollow cylinder of the implant. By excitation using an external magnetic field, collision of the sphere inside the implant produces a sound signal. Custom-made titanium implants equipped thusly were inserted in each lateral femoral epicondyle of 20 New Zealand White Rabbits. Two groups were investigated: Uncoated, machined surface versus antiadhesive surface; and calcium phosphate-coated surface versus antiadhesive surface. The sound analysis was performed postoperatively and weekly. After 4 weeks, the animals were euthanized, and the axial pull-out strengths of the implants were determined. A significant increase in the central frequency was observed for the loose implants (mean pull-out strength 21.1 ± 16.9 N), up to 6.4 kHz over 4 weeks. In comparison, the central frequency of the osseointegrated implants (105.2 ± 25.3 N) dropped to its initial value. The presented method shows potential for monitoring the osseointegration of different implant surfaces and could considerably reduce the number of animals needed for experiments. © 2014 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 32:606–612, 2014.

SummaryThe RANK/RANKL/OPG system plays an important role in the regulation of bone metabolism and bony integration around implants. The aim of this study was to analyse gene expression of OPG, RANK, and RANKL in regenerating bone during implant integration. Additionally, the effect of intermittent para - thyroid hormone (PTH) treatment was analysed. A titanium chamber was implanted in the proximal tibiae of 48 female rats. The animals received either human PTH or saline solution (NaCl). After 21 and 42 days, RNA was isolated from tissue adjacent to the implant and expression of RANK, RANKL, and OPG was analysed. After 21 days, very low expression levels of all genes were shown. In contrast, increased gene expression after 42 days was determined. Expression of RANK and RANKL was lower than that for OPG. The lower expression levels after 21 days might be due to still ossifying, fibrotic tissue around the titanium chamber. An increased OPG synthesis rate associated with decreased RANKL expression after 42 days revealed bone-forming processes. Despite significant differences in gene expression between the time points, only slight differences were observed between application of intermittent PTH and NaCl after a period of 42 days.

Background: Anatomic features of the tibial plateau (ie, posterior slope and medial concavity) have been associated with an increased risk of anterior cruciate ligament (ACL) injuries. However, it remains unclear whether these findings translate to ACL injuries sustained during recreational alpine skiing. Purpose: To investigate the association in recreational alpine skiers between prominent morphological features of the tibial plateau (slope and concavity) and the risk of sustaining an ACL injury during a noncontact incident. Study Design: Case-control study; Level of evidence, 3. Methods: Magnetic resonance imaging data of 121 recreational alpine skiers (74 female, 47 male) after a noncontact knee injury were used for this study. Of these patients, 80 (71% female [n = 57]) had a complete unilateral ACL tear (rupture group), and 41 (41% female [n = 17]) had no indications of an ACL injury (intact group). Two blinded independent examiners measured the slopes of the tibial plateau in the sagittal and coronal planes along with the maximum depth of the medial tibial plateau. Measurements were compared between sexes and between groups using t tests. Logistic regression was used to assess the associations between quantified anatomic indices and the risk of ACL injuries. Results: Within 121 study patients, female skiers had greater odds of an ACL tear compared with male skiers (odds ratio, 3.5; 95% CI, 1.6-7.8; P < .001). Female skiers were more likely to have a greater lateral tibial slope (LTS) ( P = .02) and medial tibial slope (MTS) ( P = .02) with a shallower medial tibial depth (MTD) ( P = .02) compared with male skiers. No differences between sexes were observed in the coronal tibial slope (CTS) ( P = .97). Male and female skiers as a combined group showed no associations between quantified anatomic indices and the risk of sustaining an ACL tear ( P > .10). Likewise, no significant differences were observed between the intact versus rupture group in any of the quantified anatomic indices ( P > .10). Similar findings were observed when the analyses were repeated on male and female skiers separately. Conclusion: Despite differences between sexes in knee anatomy and the injury risk, the sagittal and coronal slopes (LTS, MTS, CTS), as well as the concavity of the medial tibial plateau (MTD), were not associated with the risk of an ACL tear during a noncontact injury among recreational alpine skiers.

Hintergrund Die Therapie einer infizierten Huftendoprothese wird zunehmend zu einem wirtschaftlichen Problem. Die zusatzlichen Therapiekosten sind in den Diagnosis-Related Groups (DRG) nur unzureichend abgebildet. Ziel ist zu klaren, ob eine Kostendeckung durch das DRG-System in Deutschland moglich ist und in welchem Rahmen sich eine Uber- bzw. Unterdeckung bewegt.

Nowadays total joint replacement is an indispensable component of modern medicine. The surfaces characteristics of cementless prostheses may be altered to achieve an accelerated and enduring bony integration. Classic surface coatings bear the risk of loosening or flaking from the implant body. This risk is excluded by the chemical conversion of the naturally existing TiO2 surface layer into calcium titanate. The aim of this experimental animal study was to investigate the bony integration of implants with a new calcium titanate surface (Ca4Ti3O10) compared with a conventional standard Ti6Al4V surface. Cylindrical implants, made of titanium alloy (Ti6Al4V) were implanted in both lateral femoral condyles of New Zealand white rabbits. In each animal, an implant with and without surface treatment was inserted in a blinded manner. Animals were sacrificed after 4, 12, and 36 weeks, respectively. The axial pull-off forces were determined for 25 animals using a universal testing machine (Zwick Z010, Ulm, Germany). Furthermore, a histological analysis of the bony integration of the implants was performed in 12 specimens. In general, the pull-off forces for untreated and treated implants increased with longer survival times of the rabbits. No significant difference could be shown after 4 weeks between treated and untreated implants. After 12 weeks, the treated implants revealed a statistical significant higher pull-off force. After 36 weeks, the pull-off forces for treated and untreated implants aligned again. Titanium implants treated with calcium titanate, may offer an interesting and promising implant surface modification for endoprosthetic implants. They might lead to an accelerated osseointegration of total hip and knee replacements. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A 100A:2710–2716, 2012.

New developments of antimicrobial implant surfaces doped with copper (Cu) ions may minimize the risk of implant-associated infections. However, experimental evaluation of the Cu release is influenced by various test parameters. The aim of our study was to evaluate the Cu release characteristicsin vitroaccording to the storage fluid and surface roughness. Plasma immersion ion implantation of Cu (Cu-PIII) and pulsed magnetron sputtering process of a titanium copper film (Ti-Cu) were applied to titanium alloy (Ti6Al4V) samples with different surface finishing of the implant material (polished, hydroxyapatite and corundum blasted). The samples were submersed into either double-distilled water, human serum, or cell culture medium. Subsequently, the Cu concentration in the supernatant was measured using atomic absorption spectrometry. The test fluid as well as the surface roughness can alter the Cu release significantly, whereby the highest Cu release was determined for samples with corundum-blasted surfaces stored in cell medium.

Ceramics have increasingly been used since the 1970s in total joint arthroplasty, providing constant improvements in material properties. Nowadays, different ceramics (alumina, zirconia, and new composite materials) are available as bearing surfaces. Ceramic materials offer reduced wear rates at articulating surfaces because of their excellent friction properties, which support longevity of endoprosthetic implants. In total hip arthroplasty, long-term clinical studies confirm the advantageous properties of ceramic materials providing low risk of implant failure. In total knee arthroplasty, ceramics revealed superior experimental data concerning low wear rates as well as promising results of the first clinical applications.

Implant infections remain feared and severe complications after total hip replacement. An even higher rate of periprosthetic infections can be observed after revision surgery in comparison to primary total hip replacement. An additional threat for patients with artificial joints arises from the fact that bacteria resistant to a multitude of antibiotics are encountered with increasing frequency in the hospital setting.Among these the enterobacteria producing extended spectrum β-lactamases (ESBL) are the second most frequent group of multiresistant pathogens. ESBLs are enzymes which possess the ability to hydrolyse third and fourth generation cephalosporins resulting in a distinctive resistance against these antibiotics. Even though ESBLs were first described in the early 1980’s and now represent pathogens of utmost importance in intensive care units, they have been hardly considered in orthopedic and trauma surgery.In the present manuscript we provide an overview of the epidemiology and diagnostics of ESBL-expressing bacteria and demonstrate the difficulties in managing implant-associated infections with resistant bacteria. Furthermore, we emphasize the importance of recognizing ESBL-positive bacteria as increasingly important pathogens which require special precautions and treatment. Clinical evaluations suggest that ESBLs in orthopedic and trauma surgery are not a rare phenomenon any more.

Introduction management of intrasubstance meniscal lesions is still controversial. Intrasubstance meniscal lesions can lead to reduced sports activity and meniscal rupture. Physical therapy is often not satisfactory. Therefore new treatment methods are requested. Platelet Rich Plasma (PRP) has the ability to regenerate tissue; this was proved in several experimental studies. Whether percutaneous injections of PRP are effective in intrasubstance meniscal lesions is unknown. We hypothesize that percutaneous PRP injections lead to pain relief and halt of progression on MRI over 6 months in patients with grade 2 meniscal lesions. Materials and methods ten recreational athletes with intrasubstance meniscal lesions (grade II according to Reicher) proven by MR-Imaging (MRI) were treated by percutaneous injections of PRP in the affected meniscal area. Three sequential injections in seven day intervals were performed in every patient. All injections were performed with image converter. Follow-up MRI was done six months after last injection in every patient. Level of sports activity and amount of pain at athletic loads according to numeric rating scale (NRS-11) were noted in each patient before injections and at the time of follow up MRI after six months. The t-test was used to determine statistical differences. Results four of ten patients (40%) showed decrease of meniscal lesion in follow up MRI after six months. Nine of ten patients (90%) complained about short episodes of heavy pain after the injections with average NRS-Score of 7.9 at daily loads after the last injection. Six of ten patients (60%) showed Improvement of NRS-Score at final follow up. Average NRS-Score improved significantly (p=0.027) from 6.9 before injections to 4.5 six month after treatment. Six of ten patients (60%) reported increase of sports activity compared to the situation before injections. In four patients (40%) additional surgical treatment was necessary because of persistent knee pain or progression of meniscal lesion. Conclusions percutaneous injections of PRP have the ability to achieve pain relief and halt of progression on MRI over 6 months in patients with grade 2 meniscal lesions. Therefore it could be considered as a treatment option in patients with persisting pain. Level of evidence IV.

The purpose of this study was to compare different methods of evaluating the version of a metallic acetabular cup from plain radiographs and to compare them regarding their accuracy, inter- and intra-observer reliability. Conventional anterior–posterior radiographs were taken of a phantom-model at different defined ante- and retroversion angles of the acetabular cup. The version angles of the acetabular cup were derived according to four different established methods from the radiographs by five independent examiners. We were able to determine the radiographic version with the greatest accuracy according to a modified technique of Pettersson et al. Furthermore, we found the highest intra- and inter-observer reliability using this technique. A modified technique of Pettersson et al. broadens the spectrum of applicability for the radiographic evaluation of the version angle of metal-backed acetabular cups in comparison to the originally introduced method. In clinical practice, however, the significance of deriving the cup position from standard radiographs should not be over-estimated and therefore a computed tomography should be performed in certain critical cases.

The purpose of total hip replacement (THR) is the restoration of a painless functioning hip joint with the main focus on the biomechanical properties. Advances in surgical techniques and biomaterial properties currently allow predictable surgical results in most patients. Despite the overwhelming success of this surgical procedure, the debate continues surrounding the optimal choice of implants and fixation. Femoral and acetabular implants with varying geometries and fixation methods are currently available. Problems inherent with acrylic bone cement, however, have encouraged surgeons to use alternative surfaces to allow biologic fixation. Optimal primary and secondary fixation of cementless hip stems is a precondition for long-term stability. Important criteria to achieve primary stability are good rotational and axial stability by press-fit fixation. The objective of the cementless secondary fixation is the biological integration of the implant by bony ingrowth. Nevertheless, current investigations show excellent results of cementless fixation even in older patients with reduced osseous quality. The main advantages of cementless fixation include biological integration, reduced duration of surgery, no tissue damage by cement polymerization and reduction of intraoperative embolisms. In comparison to cemented THR both, cementless sockets and stems provide good long-term results.

In total joint replacement much effort has been made to reduce implant loosening. We investigated different implant coatings (copper integrated titanium dioxide (TiO2–Cu), titanium nitride (TiN), plasma polymerized allylamine (PPAAm), and calcium phosphate (CaP)) regarding the adhesion strength and wear resistance. Standardized scratch and adhesive tests were applied. Abrasive wear was measured with artificial bone and bone cement using a special testing machine. All tested coatings have higher bonding strengths than the 22 N/mm2 required for medical implant surface coatings by ASTM standard 4711-F. Using bone cement, wear testing revealed higher wear rates in most cases. Polished surfaces reduce the amount of wear, whereas rough surfaces highly increase the wear rate due to three-body wear, especially ceramic surfaces. In general, the application of bone cement in conjunction with modified implant surfaces can lead to an increase in wear rate.

Derzeit mussen in den ersten 10 Jahren nach Implantation durchschnittlich etwa 10 % aller Huft- und Knieendoprothesen ausgetauscht werden. Eine Revision ist meist infolge aseptischer oder septischer Lockerung der Implantate erforderlich. Zur verbesserten Osteointegration werden Implantate fur die Orthopadische Chirurgie heute zunehmend beschichtet. Beschichtungen mussen biokompatibel sein und hohen mechanischen Anforderungen gerecht werden. Hierbei spielen die Haftfestigkeit und die Abriebbestandigkeit der Schichten eine Schlusselrolle. In der vorliegenden Arbeit werden Methoden zur experimentellen Bestimmung dieser Parameter mittels verschiedener Verfahren exemplarisch an zwei innovativen Implantatbeschichtungen (TiN und TiO2-Cu) vorgestellt. Zur Ermittlung der Haftfestigkeit wurden unterschiedliche, standardisierte Verfahren verwendet. Dazu zahlten der Dornbiegeversuch, die Ritzprufung und der Stirnzugversuch. Die Abriebbestandigkeit wurde in einem speziellen Prufstand nach 1,5 Mio Lastzyklen ermittelt. Die Untersuchungen zeigten, dass die beiden getesteten TiN- und TiO2-Cu-Schichten haftfest und abriebbestandig waren. Mit den genannten Verfahren lassen sich die Haftfestigkeit und die Abriebbestandigkeit von bioaktiven, verschleismindernden oder anti-allergenen Oberflachenbeschichtungen fur Endoprothesen zuverlassig bestimmen. Methods for the mechanical characterisation of modified implant surfaces in orthopaedic surgery Nowadays, on average approximately 10 % of all hip and knee endoprostheses have to be exchanged within the first 10 years. Implant revision is often necessary following aseptic or septic loosening. Hence, today implants for orthopaedic surgery are increasingly being coated for better osseointegration. Coatings have to be biocompatible and meet high mechanical requirements, whereby the adhesive strength and the abrasive wear resistance of the coatings take on a key role. This study presents different methods to asses these parameters experimentally using two innovative coatings (TiN, TiO2-Cu) exemplary. The adhesive bonding strength of the coatings was investigated using different standardised methods, such as the arbour bending test, scratch test and the standard adhesive test. Wear resistance was determined after 1.5 million cycles in a special testing machine. The investigations showed for both coatings, TiN and TiO2-Cu, good adhesive strength and wear resistance. The adhesive strength and wear resistance of bio-active, wear reducing or anti-allergenic surface coatings can be determined reliably using the above-mentioned methods.

By means of plasma polymerization, positively charged, nanometre-thin coatings can be applied to implant surfaces. The aim of the present study was to quantify the adhesion of human bone cells in vitro and to evaluate the bone ongrowth in vivo, on titanium surfaces modified by plasma polymer coatings. Different implant surface configurations were examined: titanium alloy (Ti6Al4V) coated with plasma-polymerized allylamine (PPAAm) and plasma-polymerized ethylenediamine (PPEDA) versus uncoated. Shear stress on human osteoblast-like MG-63 cells was investigated in vitro using a spinning disc device. Furthermore, bone-to-implant contact (BIC) was evaluated in vivo. Custom-made conical titanium implants were inserted at the medial tibia of female Sprague-Dawley rats. After a follow-up of six weeks, the BIC was determined by means of histomorphometry. The quantification of cell adhesion showed a significantly higher shear stress for MG-63 cells on PPAAm and PPEDA compared to uncoated Ti6Al4V. Uncoated titanium alloyed implants showed the lowest BIC (40.4%). Implants with PPAAm coating revealed a clear but not significant increase of the BIC (58.5%) and implants with PPEDA a significantly increased BIC (63.7%). In conclusion, plasma polymer coatings demonstrate enhanced cell adhesion and bone ongrowth compared to uncoated titanium surfaces.

Implant osseointegration can currently only be assessed reliably post mortem. A novel method that relies on the principle of acoustic sound analysis was developed to enable examination of the longitudinal progress of osseointegration. The method is based on a magnetic sphere inside a hollow cylinder of the implant. By excitation using an external magnetic field, collision of the sphere inside the implant produces a sound signal. Custom-made titanium implants equipped thusly were inserted in each lateral femoral epicondyle of 20 New Zealand White Rabbits. Two groups were investigated: Uncoated, machined surface versus antiadhesive surface; and calcium phosphate-coated surface versus antiadhesive surface. The sound analysis was performed postoperatively and weekly. After 4 weeks, the animals were euthanized, and the axial pull-out strengths of the implants were determined. A significant increase in the central frequency was observed for the loose implants (mean pull-out strength 21.1 ± 16.9 N), up to 6.4 kHz over 4 weeks. In comparison, the central frequency of the osseointegrated implants (105.2 ± 25.3 N) dropped to its initial value. The presented method shows potential for monitoring the osseointegration of different implant surfaces and could considerably reduce the number of animals needed for experiments.

Objective. Implant-associated infections remain serious complications in orthopaedic and trauma surgery. A main scientific focus has thus been drawn to the development of anti-infective implant coatings. Animal models of implant-associated infections are considered helpful in thein vivotesting of new anti-infective implant coatings. The aim of the present study was to evaluate a novel animal model for generation of implant-associated infections in the tibial metaphysis of rats.Materials and Methods. A custom-made conical implant made of Ti6Al4V was inserted bilaterally at the medial proximal tibia of 26 female Sprague-Dawley rats.Staphylococcus aureusin amounts spanning four orders of magnitude and each suspended in 15 μl phosphate buffered saline (PBS) was inoculated into the inner cavity of the implant after the implantation into the defined position. Controls were treated accordingly with PBS alone. Animals were then followed for six weeks until sacrifice. Implant-associated infection was evaluated by microbiological investigation using swabs and determination of viable bacteria in the bone around the implant and the biofilm on the implants after sonification.Results. Irrespective of the initial inoculum, all animals in the various groups harbored viable bacteria in the intraoperative swabs as well as the sonication fluid of the implant and the bone samples. No correlation could be established between initially inoculated CFU and population sizes on implant surfaces at sacrifice. However, a significantly higher viable count was observed from peri-implant bone samples for animals inoculated with 106 CFU. Macroscopic signs of animal infection (pus and abscess formation) were only observed for implants inoculated with at least 105 CFUS. aureus.Discussion/Conclusion. The results demonstrate the feasibility of this novel animal model to induce an implant-associated infection in the metaphysis of rats, even with comparatively low bacterial inocula. The specific design of the implant allows an application of bacteria in reproducible numbers at well-defined contact sites to the animal bone.

Acetabular defects are a particular challenge during THR revision. Defects may be filled with autologous bone grafts, allografts or synthetic bone substitute materials. In this preliminary, retrospective study, 22 patients were treated with an oval shaped revision cup and a combination of synthetic bone substitute materials, namely hydroxyapatite and beta-tricalcium phosphate. The postoperative outcome was evaluated regarding the functional clinical outcome and quality of life using the Harris hip score, the WOMAC and the SF-36. Signs of loosening and changes of the implant position were evaluated from plain radiographs. Follow up examinations were performed after an average duration of 20.5 months (7-33 months). Postoperatively, we found a significant increase of the Harris hip score, and an increase in both the SF-36 and the WOMAC scores (without statistical significance). No radiographic signs of loosening were evident at the time of follow up. The use of synthetic bone substitute materials offers a possible alternative to the use of autologous and allogenic bone grafts in acetabular revision surgery. Further randomised controlled long-term studies are needed to verify the promising short-term results and to determine potential side effects, such as possible third body wear.

Background.An enormous economic impact can be observed for infected total knee arthroplasties (TKA). The aim of the present study was to evaluate whether a cost covering treatment of infected TKA is feasible in the German DRG System.Patients and Methods.Average total treatment costs were evaluated for infected TKA and compared with a matched pair of primary TKA. Data was generated using the health record and the hospitals’ health information system. Results were evaluated and compared regarding the total personnel and material costs with respect to the financial receipts.Results.A total of 28 patients diagnosed with an infected TKA were included. A significant increase in the average length of stay, use of medical supplies and third party medical examinations were found for the infected TKA. An average deficiency of 6,356€ per patient was observed for the infected TKA. An average profit of 927€ per patient was made performing primary TKA.Conclusions.A cost-effective treatment of infected TKA was not feasible with the receipts from the German DRG System. An adaption of the receipts has to be evaluated. Moreover, other measures have to be considered in order to achieve a comprehensive medical yet financial reasonable standard in the treatment of infected TKA and THA.

The purpose of total hip replacement (THR) is the restoration of a painless functioning hip joint with the main focus on the biomechanical properties. Advances in surgical techniques and biomaterial properties currently allow predictable surgical results in most patients. Despite the overwhelming success of this surgical procedure, the debate continues surrounding the optimal choice of implants and fixation. Femoral and acetabular implants with varying geometries and fixation methods are currently available. Problems inherent with acrylic bone cement, however, have encouraged surgeons to use alternative surfaces to allow biologic fixation. Optimal primary and secondary fixation of cementless hip stems is a precondition for long-term stability. Important criteria to achieve primary stability are good rotational and axial stability by press-fit fixation. The objective of the cementless secondary fixation is the biological integration of the implant by bony ingrowth. Nevertheless, current investigations show excellent results of cementless fixation even in older patients with reduced osseous quality. The main advantages of cementless fixation include biological integration, reduced duration of surgery, no tissue damage by cement polymerization and reduction of intraoperative embolisms. In comparison to cemented THR both, cementless sockets and stems provide good long-term results.

Implant infection remains a feared complication after total hip replacement. A higher rate of infection is observed after revision surgery. An additional threat for such patients arises from the fact that bacteria resistant to a multitude of antibiotics are encountered with increasing frequency in the hospital setting. Among them enterobacteria producing extended spectrum β-lactamases (ESBL) are the second most frequent group of multiresistant isolates. ESBLs are enzymes which hydrolyse third and fourth generation cephalosporins resulting in a distinctive resistance against these antibiotics. Even though ESBLs were first described in the early 1980's and now represent pathogens of importance in intensive care units, they have been only rarely encountered in orthopaedic and trauma surgery. We report on three cases of ESBL-associated infections in hip arthroplasty, resulting in 1) resolution of infection after removal of the hip implant, 2) death after developing a nosocomial pulmonary infection due to ESBL-producing bacteria, and 3) resolution of infection after two-stage revision. The infections, caused by multi-resistant ESBL-producing Escherichia coli and Klebsiella pneumoniae isolates, demonstrate the difficulties in managing implant associated infections with resistant bacteria, and emphasize the importance of recognizing ESBL-positive bacteria as increasingly important pathogens that require special precautions and treatment. Our observations suggest that ESBL-expressing bacteria in orthopaedic and trauma surgery are not a rare phenomenon any more.

Implant infections remain feared and severe complications after total joint arthroplasty. The incidence of multi-resistant pathogens, causing such infections, is rising continuously, and orthopaedic surgeons are confronted with an ever-changing resistance pattern. Anti-infectious surface coatings aim for a high local effective concentration and a low systemic toxicity at the same time. Antibacterial efficacy and biomechanical stability of a novel broad-spectrum anti-infectious coating is assessed in the present study. Antibacterial efficacy of a sol-gel derived titanium dioxide (TiO(2)) coating for metal implants with and without integrated copper ions as antibiotic agent was assessed against methicillin resistant Staphylococcus aureus (MRSA 27065). Both bacterial surface adhesion and growth of planktonic bacteria were assessed with bare and various TiO(2)-coated Ti6Al4V metal discs. Furthermore, bonding strength of the TiO(2) surface coating, using standard testing procedures, as well as surface roughness were determined. We found a significant reduction of the bacterial growth rate for the coatings with integrated copper ions, with highest reduction rates observed for a fourfold copper TiO(2)-coating. Pure TiO(2) without integrated copper ions did not reduce bacterial growth compared to uncoated Ti6Al4V. The coating was not detached from the substrate by standard adhesive failure testing, which indicated an excellent durability of the implant coating. The TiO(2) coating with integrated copper ions could offer a new strategy for preventing implant-associated infections, with antibacterial properties not only against the most common bacteria causing implant infections but also against multiresistant strains such as MRSA.

The acetabular cup position after total hip arthroplasty (THA) regarding its inclination and version angles are influential parameters concerning the postoperative range of motion and dislocation stability. Standard anterior-posterior X-rays remain an important diagnostic instrument to observe the postoperative outcome and to secure quality control after THA, where an optimal positioning of the patient is recommended when taking these X-rays. The purpose of this preliminary study was to determine the effect of pelvic tilting regarding the positioning calculation of the acetabular cup from standard radiographs using a modified method according to Pettersson et al. (Acta Radiol Diagn, 23:259-263, 1982). In our model experiment, we were able to show that pelvic tilting to either side causes a considerable difference between the radiographic and calculated version angles following approximately linear functions. However, pelvic tilting to either side, leads, regarding the calculation of the inclination, to an average deviation between radiographic and calculated inclination angles less than 2 degrees .