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BACKGROUND: The incidence of conversion total hip arthroplasty (cTHA) following reduction and fixation for proximal femur fractures will increase in parallel to the aging population worldwide. OBJECTIVE: The goal of this study is to report the frequency of bacterial detection and the outcome of cTHA at the authors’ institution and to analyze preoperative factors that correlate with higher rates of bacterial growth and septic revision. METHODS: 48 patients who had been converted to THA after osteosynthesis of a proximal femur fracture either by a one- or two-stage procedure were included. Septic failure rate and the frequency of bacterial detection at the time of fixation device removal were calculated. The influence of different preoperative factors was examined by the odds ratio. A receiver operating characteristic curve of c-reactive protein (CRP) for detection of bacterial growth at the time of fixation device removal was calculated. RESULTS: 18.8% patients showed positive bacterial cultures, with Staph. epidermidis being the most frequent pathogen (33.3%). Septic failure after cTHA occurred in 4.2%. Fixation with cephalomedullary nails and complications with the internal fixation showed higher odds for bacterial growth at time of cTHA. CRP for predicting bacterial growth had an area under the curve of 0.661. Implant survival was worse when temporary spacers were used. CONCLUSION: Bacterial detection rate at the time of cTHA is high, whereas septic failure rates are low. Isolated evaluation of inflammatory blood markers without other diagnostic modalities for infection is not decisive and does not justify a two-stage approach with implantation of a temporary spacer.

A novel organic–inorganic hybrid, based on SiO2-CaO-ZnO bioactive glass (BG) and polycaprolactone (PCL), associating the highly bioactive and versatile bioactive glass with clinically established PCL was examined. The BG–PCL hybrid is obtained by acid-catalyzed silica sol–gel process inside PCL solution either by direct or indirect printing. Apatite-formation tests in simulated body fluid (SBF) confirm the ion release along with the hybrid’s bone-like apatite forming. Kinetics differ significantly between directly and indirectly printed scaffolds, the former requiring longer periods to degrade, while the latter demonstrates faster calcium phosphate (CaP) formation. Remarkably, Zn diffusion and accumulation are observed at the surface within the newly formed active CaP layer. Zn release is found to be dependent on printing method and immersion medium. Investigation of BG at the atomic scale reveals the ambivalent role of Zn, capable of acting both as a network modifier and as a network former linking the BG silicate network. In addition, hMSCs viability assay proves no cytotoxicity of the Zn hybrid. LIVE/DEAD staining demonstrated excellent cell viability and proliferation for over seven weeks. Overall, this hybrid material either non-doped or doped with a metal trace element is a promising candidate to be translated to clinical applications for bone regeneration.

Introduction: The direct anterior approach (DAA) represents a well-recognized soft tissue sparing technique for primary total hip arthroplasty (THA). The feasibility and suitability of the DAA in cases of complex acetabular deformities, namely coxa profunda (CP) and protrusio acetabuli (PA), remain to be determined. Methods: A total of 188 cases of CP (100 cases) and PA (88 cases) hips undergoing primary THA via the DAA were retrospectively analyzed. Surgical and radiographic parameters were evaluated and potential complications were assessed. Finally, successful implantation was defined if surgical and radiographic parameters were well within established values of non-complex primary THA. Results: In 159 hips, the medial border of the acetabular component was transferred laterally to the ilioischial line, corresponding to a fully treated acetabular protrusion. In 23 (12.23%) cases, mild, and in 5 (2.66%) cases, moderate residual acetabular protrusion remained after THA. Postoperatively, 11.40% (PA group) and 9.00% (CP group) had a leg length discrepancy (LLD) greater than 10 mm. The mean operative time was significantly less than 60 min. A linear relationship between the BMI and operative time was observed, with an additional 0.9 min of operative time per BMI unit. Overall, complications were rare and did not differ between the two groups. Conclusion: The results of this study suggest that the DAA is a suitable approach for primary THA in patients with coxa profunda and acetabular protrusion if performed by experienced surgeons familiar with the DAA. Obese patients with acetabular protrusion may pose a significant limitation to the DAA and caution should be advised in cases of obesity.

Acetabular revision arthroplasty and osseous defect management through the direct anterior approach (DAA) with or without proximal extension.Aseptic or septic component loosening, periacetabular osseous defects, pelvic discontinuity, intrapelvic cup protrusion, anterior pseudotumors, iliopsoas tendonitis, polyethylene wear or iliopsoas abscess.Clinically relevant gluteal tendon lesions, active infection, morbid obesity, large abdominal pannus, ASA (American Society of Anesthesiologists) score III, inguinal skin infection.Electrocautery dissection is recommended to dissect the Hueter interval and to debulk pericapsular scar tissue. At all times during capsular debulking, it should be made sure not to damage the iliopsoas tendon or the neurovascular bundle. A stepwise releasing sequence can facilitate dislocation of the prosthesis. Most cases can be revised via the standard DAA but certain circumstances require an intra- or extrapelvic extension. Access to the anterior gluteal surface of the ilium can be provided using a "tensor snip". More posterior access is provided by the extensile extrapelvic approach described by Smith-Petersen. The intrapelvic Levine extension offers access to the entire visceral surface of the ilium and large parts of the anterior column.Patient revised via the intra- or extrapelvic extension and patients suffering from extensive soft tissue or osseous defects should undergo postoperative weight-bearing restrictions with 20 kg for 6 weeks.Based on our studies, there is no limitation on the type of acetabular implant that can be used in DAA revision arthroplasty. Moreover, virtually all types of periacetabular osseous defects can be managed through the approach and its extensions. Acetabular revision arthroplasty via the DAA and its extensions is safe and can result in good midterm results.OPERATIONSZIEL: Azetabuläre Wechselendoprothetik und Therapie knöcherner Defekte über den direkten anterioren Zugang und dessen proximale Erweiterungen.Aseptische oder septische Lockerung, periazetabuläre knöcherne Defekte, Beckendiskontinuität, intrapelvine Pfannenmigration, anteriore Pseudotumoren, Iliopsoas-Tendinitis, Polyethylenverschleiß, Psoasabszess.Klinisch relevante Läsionen der Glutealsehnen, aktive Infektion, krankhaftes Übergewicht, großer abdomineller Pannus, ASA Score III, Infektion in der Inguinalfalte.Scharfe Dissektion des Hueter-Intervalls und perikapsulärer Narbenstränge mit dem Elektrokauter. Hierbei sollten die Iliopsoas-Sehne und das femorale neurovaskuläre Bündel durch Haken geschützt werden. Eine schrittweise Lösung von Narbengewebe erleichtert die Luxation der Prothese. In den meisten Fällen kann der Prothesenwechsel über den anterioren Standardzugang erfolgen. Unter bestimmten Voraussetzungen ist jedoch eine intra- bzw. extrapelvine Erweiterung notwendig. Zugang zur anterioren Facies glutealis des Os ilium erreicht der Chirurg über einen „Tensor Snip“. Weiter posterior gelegene Bereiche des Os ilium können über die deutlich invasivere extrapelvine Erweiterung nach Smith-Petersen erreicht werden. Die intrapelvine Levine-Erweiterung ermöglich den Zugang zur Facies visceralis des Os ilium und zu weiten Teilen der vorderen Säule.Im Falle von ausgedehnten Knochen- und Weichteildefekten sowie nach intra- bzw. extrapelviner Erweiterung des Zuganges empfehlen wir eine Teilbelastung der operierten Extremität mit 20 kg für 6 Wochen.Eigene Studien der Autorengruppe zeigen, dass durch die Verwendung des anterioren Zuganges und seiner Erweiterungen keine Limitationen hinsichtlich des verwendbaren Implantatsystems oder des zu versorgenden Knochendefektes entstehen. Die azetabuläre Revisionsendoprothetik über den vorderen Zugang und seine Erweiterungen ist sicher und führt zu guten mittelfristigen Ergebnissen.

Purpose There is little evidence proving the concept of partial weight-bearing to be efficient and feasible. Using insole pressure measurement systems, this study aimed to explore the compliance to prescribed weight-bearing restrictions after total knee arthroplasty (TKA). Methods 50 patients after TKA were recruited in a prospective manner. They were advised to limit weight-bearing of the affected limb to 200 N. True load was measured via insole force-sensors on day one after surgery (M1) and before discharge (M2). Compliance to the rehabilitation protocol was the primary outcome parameter. Results At M1 and M2 compliance to the rehabilitation protocol was 0% und 2%, respectively. 84% (M1) and 90% (M2) of patients overloaded the affected limb during every step. The affected limb was loaded with 50% ± 14% (M1) and 57% ± 17% (M2) of body weight. Patients older than 65 loaded the affected limb on average 17% (M1) and 34% (M2) more than their younger counterparts did. This difference was even more pronounced when walking stairs up (49% increase on average) and down (53% increase on average). Conclusion Surgeons must take into consideration that the ability to maintain partial weight-bearing after TKA is highly dependent on the age of the patient and the achievable load reduction is determined by the patient’s body weight.

Purpose The Coronavirus Disease 2019 (COVID-19) may result not only in acute symptoms such as severe pneumonia, but also in persisting symptoms after months. Here we present a 1 year follow-up of a patient with a secondary tension pneumothorax due to COVID-19 pneumonia. Case presentation In May 2020, a 47-year-old male was admitted to the emergency department with fever, dry cough, and sore throat as well as acute chest pain and shortness of breath. Sputum testing (polymerase chain reaction, PCR) and computed tomography (CT) confirmed infection with the severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2). Eleven days after discharge, the patient returned to the emergency department with pronounced dyspnoea after coughing. CT showed a right-sided tension pneumothorax, which was relieved by a chest drain (Buelau) via mini open thoracotomy. For a period of 3 months following resolution of the pneumothorax the patient complained of fatigue with mild joint pain and dyspnoea. After 1 year, the patient did not suffer from any persisting symptoms. The pulmonary function and blood parameters were normal, with the exception of slightly increased levels of D-Dimer. The CT scan revealed only discrete ground glass opacities (GGO) and subpleural linear opacities. Conclusion Tension pneumothorax is a rare, severe complication of a SARS-CoV-2 infection but may resolve after treatment without negative long-term sequelae. Level of evidence V.

The classic skin incision for direct anterior approach (DAA) total hip arthroplasty (THA) is usually placed over the belly of the tensor fasciae latae (TFL) muscle parallel to the axis of the lower extremity. In the "bikini incision" technique however, a more horizontal skin incision is used and placed parallel to the skin creases, which largely corresponds to the skin's tension lines to prevent hypertrophic scarring and optimize cosmetic outcomes.Primary or secondary osteoarthritis, femoral neck fracture, aseptic acetabular component loosening with sufficient bone stock and without the need for proximal extension of the approach, head and/or liner exchange.Complex primary or revision THA requiring extensile distal and/or acetabular exposure, revision with pre-existing longitudinal DAA incision, inguinal skin infection.The skin incision, located three fingerbreadths distal to the anterior superior iliac spine (ASIS), is orientated parallel to the groin crease. One third of the incision is medial and two thirds lateral to the ASIS. Subcutaneous dissection should only be performed in the lateral two thirds of the incision to protect the main branches of the lateral femoral cutaneous nerve (LFCN). The fascia lata is opened as far lateral over the muscle belly as possible to leave the LFCN untouched within its fascial sheet. The stepwise procedure consists of three key steps: capsular exposure, capsular release, and component insertion. The approach allows for an excellent 360° exposure of the acetabulum. The femur is aligned along the incision during femoral elevation and adduction. With this technique, DAA hip arthroplasty can be performed in a less-invasive way providing best possible functional and cosmetic outcomes.No restrictions in ambulation or range of motion. Deep vein thrombosis prophylaxis.In a prospective series of 532 consecutive patients undergoing 613 primary THA with a bikini-incision in 2017, a good clinical outcome with a 2.3% incidence of wound-related problems was observed. In particular, obese patients can also benefit from the technique.OPERATIONSZIEL: Die klassische Hautinzision zur Implantation einer Hüfttotalendoprothese über den direkten anterioren Zugang wird über dem M. tensor fasciae latae angelegt und folgt in etwa der Längsachse der unteren Extremität. Bei der „Bikini-Inzision“ wird die Haut jedoch durch eine etwas horizontalere Schnittführung eröffnet, wobei die Inzision parallel zur inguinalen Hautfalte angelegt wird und damit im Wesentlichen den Hautspannungslinien folgt, um eine hypertrophe Narbenbildung zu vermeiden und für ein optimales kosmetisches Ergebnis zu sorgen.Primäre oder sekundäre Osteoarthrose, Schenkelhalsfraktur, aseptische Pfannenlockerung ohne wesentlichen Knochendefekt und ohne Notwendigkeit einer proximalen Erweiterung des Zugangs, Kopf- und/oder Inlaywechsel.Komplexe Primärendoprothetik oder Wechseleingriffe, die einer distalen und/oder proximalen Erweiterung des Zugangs bedürfen, Revisionseingriffe mit vorbestehenden kreuzenden Narbenzügen, Infektionen im Bereich der Inguinalfalten.Der Hautschnitt wird 3 Fingerbreit distal der Spina iliaca anterior superior (ASIS) angelegt und ist parallel zur Leistenfalte ausgerichtet. Ein Drittel der Inzision befindet sich medial und 2 Drittel lateral der ASIS. Die subkutane Dissektion sollte nur in den lateralen 2 Dritteln der Inzision erfolgen, um die Hauptäste des N. cutaneus femoris lateralis (LFCN) zu schützen. Die Fascia lata wird so weit lateral wie möglich über dem Muskelbauch eröffnet, um den LFCN in seiner Faszienschicht unberührt zu lassen. Die übrige Operation besteht im Wesentlichen aus 3 Schritten: Exposition der Kapsel, Kapsel-Release und Implantation der Komponenten. Der Zugang ermöglicht eine hervorragende 360°-Exposition des Azetabulums. Das Femur wird während dessen Elevation und Adduktion entlang der Inzision ausgerichtet. Mit dieser Technik ist eine minimalinvasive Implantation der Hüftendoprothese über den direkten anterioren Zugang gewährleistet bei gleichzeitig bestmöglichen funktionellen und kosmetischen Ergebnissen.Keine Einschränkungen hinsichtlich des postoperativen Bewegungsumfangs bzw. der Belastungsfähigkeit. Prophylaxe tiefer Beinvenenthrombosen.In einer prospektiven Studie mit 532 Patienten, bei denen 613 primäre Hüfttotalendoprothesen über den direkten vorderen Zugang mit einer Bikini-Inzision im Jahr 2017 implantiert wurden, waren gute klinische Ergebnisse mit einer Inzidenz postoperativer Wundheilungsstörungen von lediglich 2,3 % festzustellen. Insbesondere können auch adipöse Patienten von dieser Technik profitieren.

Tissue-sparing, minimally invasive hip arthroplasty via the direct anterior approach (DAA) using a partially neck-preserving, calcar-guided short stem.Primary and secondary osteoarthritis of the hip due to developmental dysplasia, femoroacetabular impingement, femoral head necrosis or trauma sequelae.Severe osteoporosis, active infection, American Society of Anesthesiologists (ASA) III, large metaphyseal bone defects, severe metaphyseal deformities, Dorr type C femur.Supine position on a standard operating table without extension device. Classic DAA skin incision or bikini incision distal to the inguinal fold. Blunt dissection entering the Hueter interval. Capsulotomy with capsule preservation or partial capsulectomy. Intraoperatively, it is crucial to adhere to the preoperatively planned angle and height of the femoral neck osteotomy. During femoral head removal and acetabular preparation, care must be taken to avoid iatrogenic damage to the remaining neck. After cup positioning, femoral access is achieved by release of superior capsular structures. During opening of the medullary canal and broaching, femoral torsion and axis have to be taken into account for correct rotational and axial alignment. Femoral broaches are inserted in an ascending series of sizes until the last broach is firmly lodged and is in direct contact with the antero-medial femoral neck cortex. Fluoroscopic control in two planes to check for femoral anatomic and overall offset and assess whether the implant is adequately seated with cortical support at the calcar, the distal lateral and the dorsal cortex. Implantation of the definitive implants, local infiltration analgesia and wound closure.Between 1/2011 and 12/2016 60 patients (24 female, 36 male; mean age 44 years) were treated with a partially neck-preserving short stem via the described approach. Seven patients underwent a bi-lateral procedure. Thus, 67 procedures were analysed in this retrospective cohort study. Mean follow-up was 70 months (range 28-93). The median Harris Hip Score was 48 (range 11-88) preoperatively and 98 (range 80-100) postoperatively.The minimally invasive implantation of a partially neck-preserving stem via DAA provides a safe technique with good to excellent clinical results in the mid-term.OPERATIONSZIEL: Weichteilschonende, minimal-invasive Implantation einer Hüfttotalendoprothese (Hüft-TEP) über den direkten anterioren Zugang (DAA) mit einer Schenkelhals-teilerhaltenden, Kalkar-geführten Kurzschaftprothese.Primäre und sekundäre Coxarthrose bedingt durch Hüftdysplasie, femoroacetabuläres Impingement, Hüftkopfnekrose oder Trauma.Schwere Osteoporose, Infekt, ASA(American Society of Anesthesiologists)-Status III, ausgedehnte Knochendefekte im Bereich der Metaphyse, ausgeprägte metaphysäre Deformitäten, Dorr-Typ-C-Femur OPERATIONSTECHNIK: Rückenlagerung auf einem Standardoperationstisch ohne Extensionsmodul. Klassische DAA- bzw. Bikini-Inzision distal der inguinalen Hautfalte. Stumpfe Präparation, Eingehen über das Hueter-Intervall. Kapsulotomie unter Erhalt der Kapsel oder partielle Kapsulektomie. Höhe und Winkel der Schenkelhalsosteotomie sollten mit der präoperativen Planung übereinstimmen. Während der Femurkopfentfernung und der Acetabulumpräparation ist darauf zu achten, dass kein iatrogener Schaden am verbliebenen Schenkelhals verursacht wird. Die Femurpräparation kann durch Release der superioren Kapsel erleichtert werden. Für eine korrekte Rotation und ein korrektes axiales Alignement müssen während des Raspelvorganges – aber auch schon während der Markraumeröffnung – die femorale Torsion und Achse berücksichtigt werden. Die Femurraspeln werden solange in aufsteigender Größe eingeführt bis ein fester Sitz vorliegt und die letzte Raspel möglichst nah an der anteromedialen Kortikalis zu liegen kommt. Fluoroskopisch werden in 2 Ebenen das femorale anatomische wie das globale Offset beurteilt und überprüft, ob die Raspel am Kalkar, am distal-lateraler sowie dorsaler Kortikalis aufliegt. Implantation der Originalkomponenten, Infiltrationsanalgesie und Wundverschluss.Zwischen 01/2011 und 12/2016 wurde bei 60 Patienten (24 weiblich, 36 männlich; durchschnittliches Alter 44 Jahre) die Implantation einer Hüft-TEP über den DAA mit einer Schenkelhals-teilerhaltenden Kurzschaftprothese vorgenommen. Bei 7 Patienten erfolgte eine bilaterale Versorgung, sodass in dieser retrospektiven Kohortenstudie 67 Implantate nachuntersucht werden konnten. Das durchschnittliche Follow-up betrug 70 Monate (28–93 Monate). Der mediane Harris-Hip-Score verbesserte sich von 48 (11–88) prä- auf 98 (80–100) postoperativ.Die minimal-invasive Implantation einer Kurzschaftprothese über den DAA zum Hüftgelenk ist ein sicheres Verfahren, das mittelfristig zu guten bis exzellenten klinischen Ergebnissen führt.

Surgical treatment for sacral fragility fractures using navigation-assisted screw fixation (NSF) is a modern, technically demanding procedure. Additional sacroplasty (ASP) has been shown to provide only insignificant clinical benefits for patients. This investigation highlights procedural economic aspects and evaluates results with regard to resource scarcity in order to be able to decide, whether ASP has a justification in NSF procedures beyond clinical aspects. From February 2011 to May 2017, all individuals with sacral fragility fractures surgically treated using 3D-fluoroscopy for NSF (n = 26) or NSF + ASP (n = 26) were enrolled. Outcome parameters were operative time, 3D-/2D-radiation dose, 2D-fluoroscopy time, material costs and reimbursement. In the two groups, a total of 52 individuals with 124 fragility fracture sites in sacral vertebrae I and II were surgically treated with similar numbers of screws inserted (p ≈ 0.679) requiring similar 3D- (p ≈ 0.546) and 2D-fluoroscopy radiation doses (p ≈ 0.236). In procedures with ASP, average 2D-fluoroscopy time (46.6 s vs. 32.7 s, p ≈ 0.004), and mean surgical duration (119 min vs. 96 min, p ≈ 0.011) were significantly longer. Mean implant costs (EUR 668.68 vs. EUR 204.34, p < 0.001), and reimbursement (EUR 8416.01 vs. EUR 6584.49, p ≈ 0.006) were significantly higher. Although comparison of costs and reimbursements indicated a positive financial balance, profitability was not confirmed, because financial expense for extended operative time prevented an economic advantage of procedures with ASP in this investigation. A formula was developed based on presented study data to allow similar economical decisions in other health care systems or institutions with differing resource costs.

Background: Patient education is key in the management of chronic musculoskeletal diseases like osteoarthritis (OA) of the hip and/or knee. Comparatively few studies provide information on the content of educational programs and their specific impact on patient-related parameters such as self-efficacy. The objective of this study was to evaluate the effect of two single-session educational trainings containing different motivational psychology elements. Methods: Two different types of educational training conveying the same information were designed as a one-time intervention. Training A was designed according to the Health Action Process Approach (HAPA). Training B included motivational elements based on positive images. Patients with OA of the hip or knee were randomly assigned to participate in either Training A or Training B. The patients completed questionnaires at baseline, directly after the training and 16 weeks after the training. The main evaluated parameters were disease-specific knowledge, assessed by two different questionnaires, pain-related self-efficacy and OA symptoms (WOMAC score).Results: Fifty-two patients participated. Of these, 27 were assigned to group A and 25 to group B. Disease-specific knowledge improved significantly in both groups immediately after the training and at 16 weeks follow-up. Self-efficacy was initially enhanced in both groups after the trainings but a significant improvement at 16 weeks follow-up was only found for group A. The increase in self-efficacy scores after 16 weeks was significantly higher in group A than in group B. There was a trend towards improved WOMAC scores after 16 weeks for group A but not for group B. Conclusion: The results indicate that disease-specific knowledge of OA patients can be enhanced by one-time educational trainings including motivational psychology elements. A HAPA-based training could possibly also lead to lasting improvements regarding patients’ self-efficacy and OA-related symptoms. Thus HAPA-based educational programs seem to be a promising, feasible tool to improve OA patients’ self-care. Trial registration: The study was registered with the German Clinical Trials Register (DRKS00021827).

Treatment of tricompartimental osteoarthritis (OA) using customized instruments and implants for cruciate-retaining total knee arthroplasty. Use of patient-specific instruments and implants (ConforMIS iTotalSymptomatic tricompartmental OA of the knee (Kellgren-Lawrence stage IV) with preserved posterior cruciate ligament (PCL) after unsuccessful conservative or joint-preserving surgical treatment.Knee ligament instabilities of the posterior cruciate or collateral ligaments. Infection. Relative contraindication: knee deformities15° (varus, valgus, flexion); prior partial knee replacement.Midline or parapatellar medial skin incision, medial arthrotomy; distal femoral resection with patient-specific cutting block; tibial resection using either a cutting jig for the anatomic slope or a fixed 5° slope. Balancing the knee in extension and flexion gap using patient-specific spacer. The final tibial preparation achieved with gap-balanced placement of the femoral cutting jigs. Kinematic testing using anatomic trial components. Final implant components are cemented in extension. Wound layers are sutured. Drainage is optional.Sterile wound dressing; compressive bandage. No limitation of the active and passive range of motion. Optional partial weight bearing during the first 2 weeks, then transition to full weight bearing. Follow-up directly after surgery, at 12 and 52 weeks, then every 1-2 years.Overall 60 patients with tricompartmental knee OA and preserved PCL were treated. Mean age was 66 (range 45-76) years. Minimum follow-up was 12 months. There was 1 septic revision after a low-grade infection, 1 reoperation to replace the patellar due to patellar osteoarthritis and 3 manipulations under anesthesia (MUAs) to increase range of motion. Radiographic analyses demonstrated an ideal implant fit with less than 2 mm subsidence or overhang. The WOMAC score improved from 154.8 points preoperatively to 83.5 points at 1 year and 59.3 points at 2 years postoperatively. The EuroQol-5D Score also improved from 11.1 points preoperatively to 7.7 points at 1 year postoperatively.ZIEL: Kreuzbanderhaltende Knietotalendoprothese bei Patienten mit Pangonarthrose mittels medialer Arthrotomie. Verwendung patientenspezifischer Instrumente und Implantate (ConforMIS iTotalSymptomatische Pangonarthrose (nach Kellgren und Lawrence Stadium IV) mit erhaltenem hinterem Kreuzband (HKB) nach erfolgloser konservativer und/oder operativer gelenkerhaltender Therapie.Kniebandinstabilitäten des hinteren Kreuzbands oder der Seitenbänder. Infektion. Relative Kontraindikation: Kniedeformitäten15° (Varus, Valgus, Streckdefizit) und/oder vorangegangener Teilgelenkersatz.Mittige oder medial parapatellare Hautinzision, mediale Arthrotomie. Distale femorale Resektion mit patientenspezifischem Schneideblock; Tibiaresektion mit einem Schneideblock, der einen anatomischen oder einen fixen tibialen Slope von 5° enthält. Balancierung des Kniegelenks in Streckung und Beugung mit individuell angepassten Balancierungshilfen. Finale balancierte Femurpräparation mit individuellen femoralen Schneideblöcken. Kinematische Prüfung mit anatomischen Probekomponenten. Die abschließende Tibiapräparation erfolgt mittels individueller Bohrschablone. Die finalen Implantatkomponenten werden in Streckstellung einzementiert. Schichtweiser Wundverschluss. Die Einlage einer Drainage ist optional.Sterile Wundauflagen und elastokompressive Wickelung. Keine Limitierung des aktiven und passiven Bewegungsausmaßes. Eine Teilbelastung für die ersten 2 Wochen postoperativ ist optional, bevor der Übergang zur Vollbelastung erfolgt. Verlaufskontrollen direkt postoperativ, nach 12 und 52 Wochen, danach alle 1 bis 2 Jahre.Behandelt wurden 60 Patienten mit Pangonarthrose und erhaltenem HKB. Durchschnittsalter: 66 (45–76) Jahre. Nachuntersuchungszeit mindestens 12 Monate. Es gab eine Revision nach einer Low-grade-Infektion, eine Reoperation zur Behandlung einer Retropatellararthrose mit Retropatellarersatz und 3 Narkosemobilisationen zur Verbesserung der Beweglichkeit. Röntgenkontrollen zeigten durchweg eine ideale Implantatpassform mit weniger als 2 mm Implantatüber- oder -unterstand. Der WOMAC-Gesamtscore verbesserte sich von 154,8 Punkten präoperativ auf 83,5 Punkte nach einem Jahr und auf 59,3 Punkte nach 2 Jahren postoperativ. Auch der EuroQol-5D-Score verbesserte sich von 11,1 Punkten präoperativ auf 7,7 Punkte postoperativ.

In this study we developed and validated a 3D-printed drug delivery system (3DPDDS) to 1) improve local treatment efficacy of commonly applied chemotherapeutic agents in bone cancers to ultimately decrease their systemic side effects and 2) explore its concomitant diagnostic potential. Thus, we locally applied 3D-printed medical-grade polycaprolactone (mPCL) scaffolds loaded with Doxorubicin (DOX) and measured its effect in a humanised primary bone cancer model. First, a bioengineered species-sensitive orthotopic humanized bone niche was established at the femur of NOD-SCID IL2Rγnull (NSG) mice. After 6 weeks of in vivo maturation into a humanized ossicle, Luc-SAOS-2 cells were injected orthotopically to induce local growth of Osteosarcoma (OS). After 16 weeks of OS development, a biopsy-like defect was created within the tumor tissue to locally implant the 3DPDDS with 3 different loading doses into the defect zone. Histo- and morphological analysis demonstrated a typical invasive OS growth pattern inside a functionally intact humanized ossicle as well as metastatic spread to the murine lung parenchyma. Analysis of the 3DPDDS revealed the implants' ability to inhibit tumor infiltration and showed local tumor cell death adjacent to the scaffolds without any systemic side effects. Together these results indicate a promising therapeutic and diagnostic potential of 3DPDDS in an orthotopic humanised OS tumor model.

Restoring stability after total knee arthroplasty (TKA) and improving joint function using a cemented rotating hinge system. Ligament instability and/or osseous defects (including Anderson Orthopaedic Research Institute [AORI] classification type II defects) after primary TKA or TKA revision surgery. Distal femoral or proximal tibial bowing requiring implant systems that provide femoral or tibial offset stems. Persistent periprosthetic infection. Poor therapeutic compliance. AORI type III defects. Medial arthrotomy. Femoral and tibial component removal with small saw blades and chisels. Intramedullary alignment for the tibial and femoral cuts. Debridement and removal of membranes and cement remnants. Reconstruction of joint line and correct TKA alignment. Trial reduction. Cement fixation. Unrestricted range of motion, partial weight bearing for 4 weeks. Between 2012 and 2013, 18 patients suffering from ligament insufficiency after TKA were revised using the described system and included in a prospective study protocol. The mean follow-up was 37 months (range 30–46 months). There was a significant improvement of the Oxford Knee Score (OKS) from 19 (range 7–29) preoperatively to 29 (range 10–45) postoperatively (p = 0.004). The Knee Society Score (KSS) knee assessment subscore improved from 35 (range 9–70) to 67 (range 35–97) (p = 0.002) and the pain score from 7 (range 0–50) to 24 (range 0–50) (p = 0.008).

Background: The primary aim of this study was to identify modifiable patient-related predictors of blood transfusions and perioperative complications in total hip and knee arthroplasty. Individual predictor-adjusted risks can be used to define preoperative treatment thresholds. Methods: We performed this retrospective monocentric study in orthopaedic patients who underwent primary total knee or hip arthroplasty. Multivariate logistic regression models were used to assess the predictive value of patient-related characteristics. Predictor-adjusted individual risks of blood transfusions and the occurrence of any perioperative adverse event were calculated for potentially modifiable risk factors. Results: 3754 patients were included in this study. The overall blood transfusion and complication rates were 4.8% and 6.4%, respectively. Haemoglobin concentration (Hb, p &lt, 0.001), low body mass index (BMI, p &lt, 0.001) and estimated glomerular filtration rate (eGFR, p = 0.004) were the strongest potentially modifiable predictors of a blood transfusion. EGFR (p = 0.001) was the strongest potentially modifiable predictor of a complication. Predictor-adjusted risks of blood transfusions and acute postoperative complications were calculated for Hb and eGFR. Hb = 12.5 g/dL, BMI = 17.6 kg/m2, and eGFR = 54 min/mL were associated, respectively, with a 10% risk of a blood transfusion, eGFR = 59 mL/min was associated with a 10% risk of a complication. Conclusion: The individual risks for blood transfusions and acute postoperative complications are strongly increased in patients with a low preoperative Hb, low BMI or low eGFR. We recommend aiming at a preoperative Hb ≥ 13g/dL, an eGFR ≥ 60 mL/min and to avoid a low BMI. Future studies must show if a preoperative increase of eGFR and BMI is feasible and truly beneficial.

Cartilage offers limited regenerative capacity. Cell-based approaches have emerged as a promising alternative in the treatment of cartilage defects and osteoarthritis. Due to their easy accessibility, abundancy, and chondrogenic potential mesenchymal stromal cells (MSCs) offer an attractive cell source. MSCs are often combined with natural or synthetic hydrogels providing tunable biocompatibility, biodegradability, and enhanced cell functionality. In this review, we focused on the different advantages and disadvantages of various natural, synthetic, and modified hydrogels. We examined the different combinations of MSC-subpopulations and hydrogels used for cartilage engineering in preclinical and clinical studies and reviewed the effects of added growth factors or gene transfer on chondrogenesis in MSC-laden hydrogels. The aim of this review is to add to the understanding of the disadvantages and advantages of various combinations of MSC-subpopulations, growth factors, gene transfers, and hydrogels in cartilage engineering.

Background: During total knee arthroplasty (TKA), one of the key alignment factors to pay attention to is the posterior tibial slope (PTS). The PTS clearly influences the kinematics of the knee joint but must be adapted to the coupling degree of the specific TKA design. So far, there is hardly any literature including clear recommendations for how surgeons should choose the PTS in a medial stabilized (MS) TKA. The aim of the present study is to investigate the effects of different degrees of PTS on femorotibial kinematics in MS TKA. Materials and Methods: An MS TKA was performed in seven fresh-frozen human specimens successively with 0°, 3°, and 6° of PTS. After each modification, weight-bearing deep knee flexion (30–130°) was performed, and femorotibial kinematics were analyzed. Results: A lateral femoral rollback was observed for all three PTS modifications. With an increasing PTS, the tibia was shifted more anteriorly on the lateral side (0° PTS anterior tibial translation −9.09 (±9.19) mm, 3° PTS anterior tibial translation −11.03 (±6.72) mm, 6° PTS anterior tibial translation 11.86 (±9.35) mm). No difference in the tibial rotation was found for the different PTS variants. All PTS variants resulted in internal rotation of the tibia during flexion. With a 3° PTS, the design-specific medial rotation point was achieved more accurately. Conclusions: According to our findings, we recommend a PTS of 3° when implanting the MS prosthesis used in this study.

This study aimed to investigate the effects of recombinant human bone morphogenetic protein (rhBMP-7) on human cancellous bone grafts (BGs) while differentiating between anabolic and catabolic events. Human BGs alone or supplemented with rhBMP-7 were harvested 14 weeks after subcutaneous implantation into NOD/Scid mice, and studied via micro-CT, histomorphometry, immunohistochemistry and flow cytometry. Immunohistochemical staining for human-specific proteins made it possible to differentiate between grafted human bone and newly formed murine bone. Only BGs implanted with rhBMP-7 formed an ossicle containing a functional hematopoietic compartment. The total ossicle volume in the BMP+ group was higher than in the BMP− group (835 mm3 vs. 365 mm3, respectively, p

Peritoneal invasion through the mesothelial cell layer is a hallmark of ovarian cancer metastasis. Using tissue engineering technologies, we recreated an ovarian tumor microenvironment replicating this aspect of disease progression. Ovarian cancer cell-laden hydrogels were combined with mesothelial cell-layered melt electrospun written scaffolds and characterized with proliferation and transcriptomic analyses and used as intraperitoneal xenografts. Here we show increased cancer cell proliferation in these 3D co-cultures, which we validated using patient-derived cells and linked to peritoneal tumor growth in vivo. Transcriptome-wide expression analysis identified IGFBP7, PTGS2, VEGFC and FGF2 as bidirectional factors deregulated in 3D co-cultures compared to 3D mono-cultures, which we confirmed by immunohistochemistry of xenograft and patient-derived tumor tissues and correlated with overall and progression-free survival. These factors were further increased upon expression of kallikrein-related proteases. This clinically predictive model allows us to mimic the complexity and processes of the metastatic disease that may lead to therapies that protect from peritoneal invasion or delay the development of metastasis.

Mobilization on the day of surgery after total hip arthroplasty (THA) is widely used. However, elderly, obese and severely diseased patients are often excluded from early mobilization. Therefore, it was our aim to investigate the effect of mobilization on the day of surgery with focus on these patients.167 patients underwent THA via direct anterior approach. Exclusion criterion was the use of wound drainage. The patients were randomly allocated to two groups. Day 0 group was mobilized 4 hours after surgery, day 1 group the day after surgery. Primary outcome was the time to readiness for discharge (TRD). Secondary outcome was the occurrence of adverse events (vertigo, nausea, vomiting, severe pain) on the day of surgery. Group comparisons were calculated with respect to elderly (age ≥75 years), obese (BMI ≥30 kg/mTRD was shorter in day 0 group (3.25 vs 3.99 days, P.01). The rate of adverse events on the day of surgery was similar in both groups (0.28 vs 0.25, P = .73). TRD differences were higher within all subgroups (3.85vs4.81; 3.25vs4.39; 4.08vs5.11days) while the rate of immediate adverse events was reduced (0.15vs0.24; 0.25vs0.3; 0.25vs0.33). Within 90 days 3 patients of group 0 underwent revision surgery, none of group 1 (P = .12).Mobilization on the day of surgery reduces the TRD without increasing the rate of immediate adverse events, regardless of age, BMI and ASA score. Future studies are needed to investigate if early mobility increases the 90-days complication rate.

Prostate cancer (PCa) is the second most commonly diagnosed cancer in men, and bone is the most frequent site of metastasis. The tumor microenvironment (TME) impacts tumor growth and metastasis, yet the role of the TME in PCa metastasis to bone is not fully understood. We used a tissue-engineered xenograft approach in NOD-scid IL2Rγnull (NSG) mice to incorporate two levels of humanization; the primary tumor and TME, and the secondary metastatic bone organ. Bioluminescent imaging, histology, and immunohistochemistry were used to study metastasis of human PC-3 and LNCaP PCa cells from the prostate to tissue-engineered bone. Here we show pre-seeding scaffolds with human osteoblasts increases the human cellular and extracellular matrix content of bone constructs, compared to unseeded scaffolds. The humanized prostate TME showed a trend to decrease metastasis of PC-3 PCa cells to the tissue-engineered bone, but did not affect the metastatic potential of PCa cells to the endogenous murine bones or organs. On the other hand, the humanized TME enhanced LNCaP tumor growth and metastasis to humanized and murine bone. Together this demonstrates the importance of the TME in PCa bone tropism, although further investigations are needed to delineate specific roles of the TME components in this context., McGovern et al. establish an orthotopic, humanized prostate cancer model to study bone metastasis. The authors demonstrate that a humanized tumor microenvironment (TME) influences the metastatic spread of cancer cells to tissue-engineered bone, highlighting the importance of the TME in prostate cancer metastasis to bone.

Current xenograft animal models fail to accurately replicate the complexity of human bone disease. To gain translatable and clinically valuable data from animal models, new in vivo models need to be developed that mimic pivotal aspects of human bone physiology as well as its diseased state. Above all, an advanced bone disease model should promote the development of new treatment strategies and facilitate the conduction of common clinical interventional procedures. Here we describe the development and characterisation of an orthotopic humanised tissue-engineered osteosarcoma (OS) model in a recently genetically engineered x-linked severe combined immunodeficient (X-SCID) rat. For the first time in a genetically modified rat, our results show the successful implementation of an orthotopic humanised tissue-engineered bone niche supporting the growth of a human OS cell line including its metastatic spread to the lung. Moreover, we studied the inter- and intraspecies differences in ultrastructural composition of bone and calcified tissue produced by the tumour, pointing to the crucial role of humanised animal models.

Proximal femoral replacement (PFR) is a salvage procedure originally developed for reconstruction after resection of sarcomas and metastatic cancer. These techniques can also be adapted for the treatment of non-oncologic reconstruction for cases involving massive proximal bone loss. The direct anterior approach (DAA) is readily utilized for revision total hip arthroplasty (THA), but there have been few reports of its use for proximal femoral replacement.Aseptic, septic femoral implant loosening, periprosthetic femoral fracture, oncologic lesions of the proximal femur. The most common indication for non-oncologic proximal femoral placement is a severe femoral defect Paprosky IIIB or IV.Infection.In contrast to conventional DAA approaches and extensions, we recommend starting the approach 3 cm lateral to the anterior superior iliac spine and performing a straight incision directed towards the fibular head. After identification and incision of the tensor fasciae lata proximally and the lateral mobilization of the iliotibial tract distally, the vastus lateralis muscle can be retracted medially as far as needed. Special care should be taken to avoid injuries to the branches of the femoral nerve innervating the vastus lateralis muscle. If required, the distal extension of the DAA can continue all the way to the knee to allow implantation of a total femoral replacement. The level of the femoral resection is detected with an x‑ray. In accordance with preoperative planning, the proximal femur is resected. Ream and broach the distal femoral fragment to the femoral canal. With trial implants in place, leg length, anteversion of the implant and hip stability are evaluated. It is crucial to provide robust reattachment of the abductor muscles to the PFR prosthesis. Mesh reinforcement can be used to reinforce the muscular attachment if necessary.We typically use no hip precautions other than to limit combined external rotation and extension for 6 weeks. In most cases, full weight bearing is possible after surgery.A PFR was performed in 16 patients (mean age: 55.1 years; range 17-84 years) using an extension of the DAA. The indication was primary bone sarcoma in 7 patients, metastatic lesion in 6 patients and massive periprosthetic femoral bone loss in 3 patients. Complications related to the surgery occurred in 2 patients (both were dislocation). Overall, 1 patient required reoperation and 1 patient died because of his disease. Mean follow-up was 34.5 months.OPERATIONSZIEL: Die proximale Femurersatzprothese ist oft eine Rettungsprozedur in der Endoprothetik. Ursprünglich wurde diese Technik für Rekonstruktionen nach Sarkom- oder Metastasenresektion verwendet. Diese Techniken können allerdings auch für nichtonkologische Rekonstruktionen verwendet werden in Fällen mit massivem Knochenverlust im Bereich des proximalen Femurs. Der direkte vordere Zugang (DAA) wird regelmäßig für die Revisionsendoprothetik der Hüfte verwendet, aber es gibt nur wenige Berichte über die Technik des proximalen Femurersatzes über diesen Zugang.Aseptische Femurimplantatlockerung, periprothetische Femurfraktur, Sarkom im Bereich des proximalen Femurs, Metastase im Bereich des proximalen Femurs. Die häufigste nichtonkologische Indikation ist ein femoraler Defekt nach Paprosky IIIB oder IV.Infektionen.Im Gegensatz zum Standard-DAA-Zugang und zu Erweiterungen empfehlen wir bei der Implantation einer proximalen Femurersatzprothese einen geraden Hautschnitt, beginnend 3 cm lateral der Spina iliaca anterior superior in Richtung des Fibulaköpfchens. Nach Identifikation und Inzision der Faszie des M. tensor fasciae latae proximal und Mobilisation des Tractus iliotibialis nach lateral distal, kann der M. vastus lateralis nach medial weggehalten werden. Um Verletzungen der Äste des N. femoralis zu vermeiden, die den M. vastus lateralis innervieren, sollte bei der Präparation besonders darauf geachtet werden. Nach distal kann der DAA-Zugang bis zum Kniegelenk erweitert werden, so dass sogar die Implantation einer totalen Femurprothese möglich ist. Die Resektionshöhe sollte nun bestimmt, mittels einer Röntgenaufnahme kontrolliert und mit der präoperativen Planung abgeglichen werden. Mit Hilfe von Probeimplantaten können nun die Beinlänge, die Anteversion des Femurs und die Luxationswahrscheinlichkeit überprüft werden. Es ist unbedingt notwendig, die Abduktoren suffizient am proximalen Femur zu refixieren. Hierzu kann ein Anbindungsschlauch verwendet werden.Bewegungseinschränkungen bezüglich der Außenrotation und Extension für 6 Wochen. In den meisten Fällen ist Vollbelastung nach der Operation möglich.Die Implantation einer proximalen Femurersatzprothese wurde in 16 Patienten (Durchschnittsalter: 55,1 Jahre; Min. 17 Jahre; Max. 84 Jahre) mit einer Erweiterung des DAA durchgeführt. Indikation für die Operation war bei 7 Patienten ein primäres Knochensarkom, bei 6 Patienten eine metastatische Läsion des proximalen Femurs und bei 3 Patienten ein massiver periprothetischer Knochenverlust im Bereich des proximalen Femurs. Operationsbezogene Komplikationen ereigneten sich bei 2 Patienten (Luxation). Ein Patient verstarb aufgrund seiner Grundkrankheit (Sarkom). Die durchschnittliche Nachuntersuchungszeit betrug 34,5 Monate.

The advantages of the direct anterior approach (DAA) in primary total hip arthroplasty as a minimally invasive, muscle-sparing, internervous approach are reported by many authors. Therefore, the DAA has become increasingly popular for primary total hip arthroplasty (THA) in recent years, and the number of surgeons using the DAA is steadily increasing. Thus, the question arises whether femoral revisions are possible through the same interval.Aseptic, septic femoral implant loosening, malalignment, periprosthetic joint infection or periprosthetic femoral fracture.A draining sinus from another approach.The incision for the primary DAA can be extended distally and proximally. If necessary, two releases can be performed to allow better exposure of the proximal femur. The DAA interval can be extended to the level of the anterior superior iliac spine (ASIS) in order to perform a tensor release. If needed, a release of the external rotators can be performed in addition. If a component cannot be explanted endofemorally, and a Wagner transfemoral osteotomy or an extended trochanteric osteotomy has to be performed, the skin incision needs to be extended distally to maintain access to the femoral diaphysis.Depending on the indication for the femoral revision, ranging from partial weight bearing in cases of periprosthetic fractures to full weight bearing in cases of aseptic loosening.In all, 50 femoral revisions with a mean age of 65.7 years and a mean follow-up of 2.1 years were investigated. The femoral revision was endofemoral in 41 cases, while a transfemoral approach with a lazy‑S extension was performed in 9 patients. The overall complication rate was 12% (6 complications); 3 patients or 6% of the included patients required reoperations. None of the implanted stems showed a varus or valgus position. There were no cases of mechanical loosening, stem fracture or subsidence. Median WOMAC (Western Ontario and McMaster Universities Osteoarthritis Index) score before surgery improved significantly from preoperative (52.5) to postoperative (27.2).OPERATIONSZIEL: Die Vorteile des direkten vorderen Zugangs zur Hüfte („direct anterior approach“, DAA) bei der primären totalen Hüftendoprothetik als minimal-invasiver, muskelschonender und internervaler Zugang werden von zahlreichen Autoren beschrieben. Daher wurde der DAA für primäre Hüftendoprothesen in den letzten Jahren zunehmend beliebter, und immer mehr Ärzte entscheiden sich für diesen Zugang. Somit stellt sich die Frage, ob femorale Revisionen durch dasselbe Operationsintervall durchgeführt werden können.Aseptische oder septische Femurimplantatlockerung, Fehlstellung, periprothetische Infektion oder periprothetische Femurfraktur.Fistel von einem anderen Zugang.Die Inzision des primären DAA kann distal und proximal erweitert werden. Falls notwendig, können zwei Muskelablösungen erfolgen, um das proximale Femur besser freizulegen. Das DAA-Intervall kann bis zur Spina iliaca anterior superior erweitert werden, um den Tensor abzulösen. Falls notwendig, können die Außenrotatoren zusätzlich abgelöst werden. Falls eine Komponente endofemoral nicht explantiert werden kann und eine transfemorale Osteotomie nach Wagner oder eine erweiterte Trochanterosteotomie durchgeführt werden muss, sollte die Hautinzision distal erweitert werden, um den Zugang zum Femurschaft aufrechtzuerhalten.Das postoperative Management ist abhängig von der Indikation für die Femurrevision und reicht von Teilbelastung bei periprothetischen Frakturen bis zur Vollbelastung bei aseptischen Lockerungen.Insgesamt wurden 50 Femurrevisionen mit einem durchschnittlichen Alter 65,7 Jahren und einem durchschnittlichen Nachuntersuchungszeitraum von 2,1 Jahren untersucht. Eine endofemorale Revision konnte in 41 Fällen durchgeführt werden, während ein transfemoraler Zugang mit Lazy-S-Extension bei 9 Patienten durchgeführt wurde. Die Komplikationsrate betrug 12 % (6 Komplikationen). Drei Patienten benötigten eine Revisionsoperation. Keiner der implantierten Schäfte zeigte eine varische oder valgische Positionierung. Ebenso zeigte keiner der implantierten Schäfte eine mechanische Lockerung, Schaftfraktur oder eine Sinterung. Der mediane WOMAC(Western Ontario and McMaster Universities Osteoarthritis Index)-Score verbesserte sich im präoperativen (52,5) zu postoperativen Vergleich (27,2) signifikant.

SummaryVitamin D deficiency is a global health problem of enormous and increasing dimensions. In the past decades, numerous studies have centered on the role of vitamin D in the pathogenesis and course of many diseases including several types of cancer. Indeed, vitamin D has been widely acknowledged to be involved in the regulation of cell proliferation, differentiation and apoptosis in numerous cancer cells. While the full range of molecular mechanisms involveld in cancer cell growth and progression remains to be elucidated, recent research has deepened our understanding of the processes that may be affected by vitamin D or vitamin D deficiency.In this review, we consider the properties of bone that enable cancer cells to grow and thrive within the skeleton, and the role of vitamin D and the vitamin D receptor in the process of primary and secondary cancer growth in bone.

The clinical and radiographic outcomes after revision total knee arthroplasty (TKA) for instability with two rotating hinge knee prostheses were compared. Fifty-one patients revised for TKA instability were prospectively randomized to either the Link Endo-Model (N = 26) or the EnduRo (N = 25). Clinical and radiographic outcome scores were compared pre-operatively and at 12 months’ follow-up. Failure mechanisms were recorded. Age, BMI, operation, and tourniquet-time did not differ significantly between groups. Radiographic evaluation demonstrated correct implant alignment. The Endo-Model was implanted with a higher slope (p = 0.0001) and the mechanical lower extremity axis was straighter (p = 0.0323). Except for the patient function Knee Society Score and the Physical Health Component Summary Score in the EnduRo group, all clinical scores (range of motion/knee function Knee Society Score/Oxford Knee Score/Visual Analog Scale/Mental Health Component Summary Score) improved significantly for both prosthesis designs during the follow-up period. The Visual Analog Scale and Mental Health Component Summary score were significantly better (p = 0.045 and p = 0.0148) in the Endo-Model group at the 12 months’ follow-up. In the EnduRo group 2 patients (8%) and in the Endo-Model group 1 patient (3.8%) had to be revised for infection. Both prosthetic designs provide significant improvement in pain and function scores after TKA revision for gross instability. We found slight advantages in favor of the Endo-Model; however, no design yielded superior results throughout the study.

Tissue engineering provides the possibility of regenerating damaged or lost osseous structures without the need for permanent implants. Within this context, biodegradable and bioresorbable scaffolds can provide structural and biomechanical stability until the body's own tissue can take over their function. Additive biomanufacturing makes it possible to design the scaffold's architectural characteristics to specifically guide tissue formation and regeneration. Its nano-, micro-, and macro-architectural properties can be tailored to ensure vascularization, oxygenation, nutrient supply, waste exchange, and eventually ossification not only in its periphery but also in its center, which is not in direct contact with osteogenic elements of the surrounding healthy tissue. In this article we provide an overview about our conceptual design and process of the clinical translation of scaffold-based bone tissue engineering applications.

Current in vivo models for investigating human primary bone tumors and cancer metastasis to the bone rely on the injection of human cancer cells into the mouse skeleton. This approach does not mimic species-specific mechanisms occurring in human diseases and may preclude successful clinical translation. We have developed a protocol to engineer humanized bone within immunodeficient hosts, which can be adapted to study the interactions between human cancer cells and a humanized bone microenvironment in vivo. A researcher trained in the principles of tissue engineering will be able to execute the protocol and yield study results within 4-6 months. Additive biomanufactured scaffolds seeded and cultured with human bone-forming cells are implanted ectopically in combination with osteogenic factors into mice to generate a physiological bone 'organ', which is partially humanized. The model comprises human bone cells and secreted extracellular matrix (ECM); however, other components of the engineered tissue, such as the vasculature, are of murine origin. The model can be further humanized through the engraftment of human hematopoietic stem cells (HSCs) that can lead to human hematopoiesis within the murine host. The humanized organ bone model has been well characterized and validated and allows dissection of some of the mechanisms of the bone metastatic processes in prostate and breast cancer.

Bicompartmental knee replacement in patients with combined osteoarthritis (OA) of the medial or lateral and patellofemoral compartment. Patient-specific instruments and implants (ConforMIS iDuo™) with a planning protocol for optimal implant fit. Bicompartmental OA of the knee (Kellgren & Lawrence stage IV) affecting both the medial or lateral and patellofemoral compartment after unsuccessful conservative or joint-preserving surgery. Tricompartmental OA, knee ligament instabilities, knee deformities >15° (varus, valgus, extension deficit). Relative contraindication: body mass index >40; prior unicompartmental knee replacement or osteotomies. Midline or parapatellar medial skin incision, medial arthrotomy; identify mechanical contact zone of the intact femoral condyle (linea terminalis); remove remaining cartilage and all osteophytes that may interfere with the correct placement of the individually designed instruments. Balance knee in extension with patient-specific balancing chips. Resection of proximal tibia with an individual cutting block; confirm axial alignment using an extramedullary alignment guide, balance flexion gap using spacer blocks in 90° flexion. Final femur preparation with resection of the anterior trochlea. After balancing and identification of insert heights, final tibial preparation is performed. Implant is cemented in 45° of knee flexion. Remove excess cement and final irrigation, followed by closure. Sterile wound dressing; compressive bandage. No limitation of active/passive range of motion (ROM). Partial weight bearing the first 2 weeks, then transition to full weight bearing. Follow-up directly after surgery, at 12 and 52 weeks, then every 1–2 years. In all, 44 patients with bicompartmental OA of the medial and patellofemoral compartment were treated. Mean age 59 years. Minimum follow-up 12 months. Implant converted to TKA due to tibial loosening (1 patient); patella resurfacing (3 patients). No further revisions or complications. Radiographic analyses demonstrated ideal fit of the implant with less than 2 mm subsidence or overhang. KSS pain scores improved from preoperatively 5.7 to 1.7 postoperatively with level walking, and from 7.3 preoperatively to 2.8 postoperatively with climbing stairs or inclines. The WOMAC score improved from preoperatively 43 to 79 postoperatively.