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Informative, participatory clinical decision-making needs to combine both skills and expertise as well as current scientific evidence. The flood of digital information makes it difficult in everyday clinical practice to keep up to date with the latest publications. This article provides assistance for coping with this problem. A basic understanding of prior and posterior probabilities as well as systematic error (bias) makes it easier to weigh up the benefits and risks, e.g. of a (surgical) intervention compared to a nonsurgical treatment. Randomized controlled trials (RCT, with all modern modifications) deliver undistorted results but in orthopedic and trauma surgery can lead to a heavily selected nonrepresentative sample and the results must be confirmed or refuted by further, independent RCTs. Large-scale observational data (e.g. from registries) can be modelled in a quasi-experimental manner and accompany RCTs in health technology assessment.Für eine informierte, partizipative ärztliche Entscheidungsfindung müssen Sie neben Ihrem Erfahrungswissen aktuelle wissenschaftliche Daten berücksichtigen. Die digitale Informationsflut macht es im klinischen Alltag allerdings schwer, immer auf dem Stand des Wissens zu bleiben. Der Beitrag bietet einige Hilfen an, wie mit diesem Problem umgegangen werden kann. Ein grundlegendes Verständnis über Vor- und Nachwahrscheinlichkeiten sowie systematische Fehler (Bias) erleichtert die Abwägung zwischen Nutzen und Risiko z. B. einer (chirurgischen) Intervention im Vergleich zu einer nichtoperativen Therapie. Randomisierte Studien („randomized controlled trials“, RCT, mit allen modernen Modifikationen) liefern unverzerrte Ergebnisse, führen in Orthopädie und Unfallchirurgie evtl. zu einer stark selektierten, nichtrepräsentativen Stichprobe, und ihre Resultate müssen durch weitere, unabhängige RCT bestätigt oder widerlegt werden. Große beobachtende Datenmengen (z. B. aus Registern) können quasiexperimentell modelliert werden und RCT in der Gesundheitstechnologiebewertung flankieren.

Das medizinische Wissen wachst sehr schnell. Doch welche Forschungsergebnisse in Orthopadie und Unfallchirurgie sind tatsachlich dazu geeignet, Therapieentscheidungen im Alltag zu verandern? Die evidenzbasierte Medizin sucht dazu verlassliche Antworten und stutzt sich bei der Bewertung von wissenschaftlichen Daten auf eine eigene Auswertesystematik mit Qualitatskriterien und definierten Maszahlen. Es geht im Kern darum, durch eine strukturierte Analyse den wahren Patientennutzen aus Studienergebnissen herauszufiltern, um daraus einen Algorithmus zur Losung klinischer Probleme abzuleiten. Die klinische Expertise, das Wissen und die Urteilskraft von Orthopaden und Unfallchirurgen spielen bei der Bewertung der errechneten evidenzbasierten Kennzahlen eine zentrale Rolle.

Static pelvic tilt impacts functional cup position in total hip arthroplasty (THA). In the current study we investigated the effect of kinematic pelvic changes on cup position. In the course of a prospective controlled trial postoperative 3D-computed tomography (CT) and gait analysis before and 6 and 12 months after THA were obtained in 60 patients. Kinematic pelvic motion during gait was measured using Anybody Modeling System. By fusion with 3D-CT, the impact of kinematic pelvic tilt alterations on cup anteversion and inclination was calculated. Furthermore, risk factors correlating with high pelvic mobility were evaluated. During gait a high pelvic range of motion up to 15.6° exceeding 5° in 61.7% (37/60) of patients before THA was found. After surgery, the pelvis tilted posteriorly by a mean of 4.0 ± 6.6° (p < .001). The pelvic anteflexion led to a mean decrease of −1.9 ± 2.2° (p < .001) for cup inclination and −15.1 ± 6.1° (p < .001) for anteversion in relation to the anterior pelvic plane (APP). Kinematic pelvic changes resulted in a further change up to 2.3° for inclination and up to 12.3° for anteversion. In relation to the preoperative situation differences in postoperative cup position ranged from −4.4 to 4.6° for inclination and from −7.8 to 17.9° for anteversion, respectively. Female sex (p < .001) and normal body weight (p < .001) correlated with high alterations in pelvic tilt. Kinematic pelvic changes highly impact cup anteversion in THA. Surgeons using the APP as reference should aim for a higher anteversion of about 15° due to the functional anteflexion of the pelvis during gait.

In der primaren Endoprothetik des Huftgelenkes wird der Erfolg der Operation masgeblich von der Primarstabilitat des Implantates und der Wiederherstellung der patientenindividuellen Gelenkbiomechanik bestimmt. Die dreidimensionale (Patho‑)Anatomie, Grosenverhaltnisse, Geometrie und Form des Azetabulums und proximalen Femurs sind bei Patienten mit fortgeschrittener Koxarthrose hochvariabel. Eine prazise praoperative Planung gilt daher als wesentliche Voraussetzung jedes Eingriffes. Wissenschaftliche Ergebnisse belegen uber Surrogatparameter (Offset und Beinlange) patientenzentrierte Vorteile bei der Rekonstruktion einer funktionellen Gelenkgeometrie nach endoprothetischer Versorgung des Huftgelenks. Die haufig in der Literatur zitierten „Zielzonen“ fur die Positionierung der Pfanne stehen zunehmend im Fokus der wissenschaftlichen Diskussion. Individuell angepasste Zielzonen fur die Implantatpositionierung ermoglichen potentiell eine Verringerung von Anschlagsphanomenen. Patienten nach Spondylodesen bzw. pathologischem spinopelvinem Alignement bedurfen im Besonderen einer patientenindividuellen Vorbereitung, Operationstechnik und Implantatwahl, um das Risiko fur postoperative Instabilitaten zu verringern.

Computerassistierte Operationstechniken stellen in der Huftendoprothetik eine relativ neue Entwicklung dar, die durch den technischen Fortschritt in den letzten zwei Jahrzehnten beflugelt wurde. Mit Navigation und Robotik lassen sich vorgegebene Zielwerte bei der Pfannenpositionierung und der biomechanischen Rekonstruktion von Beinlange und Offset im Vergleich zur „Freihandimplantation“ mit hoherer Prazision erreichen. Der optimale Zielbereich dieser Parameter ist Gegenstand wissenschaftlicher Diskussion. Operationstechniken mit digitaler Unterstutzung benotigen eine entsprechende Lernkurve sowie einen relevanten finanziellen und zeitlichen Mehraufwand, der sich gegenwartig im DRG-System nicht widerspiegelt. Auch deshalb sind diese Verfahren bislang noch nicht in der klinischen Routine angekommen und es liegen unter evidenzbasierter Betrachtungsweise bislang zwar wenige, aber dennoch bemerkenswerte vergleichende Untersuchungen vor. Ob sich aus den daraus ablesbaren Fortschritten im langfristigen Verlauf auch verlangerte Standzeiten mit hoherer Patientenzufriedenheit ablesen lassen, konnten zukunftig systematische Auswertungen von Registerdaten mit evidenzbasierten Methoden zeigen.

Purpose: Football players have a high risk of leg muscle injuries, especially when exposed to mental stress. Hence, this study investigated the musculoskeletal response of elite youth football play...

Purpose Polyethylene (PE) wear remains a common reason for revision surgery following total hip arthroplasty (THA). An established treatment method is isolated liner exchange in a well-fixed acetabular cup and entails a known high risk of hip dislocation after revision surgery. The purpose of this retrospective study was to determine the rate of hip dislocation after liner exchange. Methods Patients were included if (1) the PE liner was removable, (2) the acetabular shell was stable with acceptable orientation, (3) no osteolysis around the acetabular cup was found and (4) no dislocation of the THA occurred before revision surgery. We reviewed medical histories and performed radiological measurements using Einzel-Bild-Röntgen-Analyse (EBRA) software. EBRA measurements and statistical investigations were performed by two independent investigators. Results A total of 82 patients were included in our study. Mean follow-up was six (range: 3.6–9.9) years. In 13 (15.8%) patients THA dislocations occurred at a mean postoperative period of 20.2 (range: 1–44) weeks after revising the PE liner. This is equivalent to an absolute risk increase of 16% after revision surgery, which results in a number needed to harm of 6. This means that every sixth patient with isolated liner exchange can expect to experience dislocation due to wear. Conclusion In conclusion, isolated exchange of the polyethylene liner because of wear showed a high risk of dislocation and further cup revision. Our results suggest that the threshold for revising well-fixed components in the case of liner wear should be lowered. Trial Registration number and date of registration Number: 20140710-1012 and Date: 2016-03-09.

The optimal 3D positioning of the prosthesis components is of great importance for the stability and function of a total hip endoprosthesis. Pelvic tilt has a particular influence on the position of the implant. In order to use intraoperatively the knowledge on pelvic kinematics gained through preoperative imaging procedures and movement analyses, "image-based" and "image-free" robotic and navigation procedures are available. With the "image-based" procedures, a 3D CT scan serves as the surgeon's basis for operative planning. The "image-free" procedures are based on the principles of stereotaxy. In the future, information about static and dynamic pelvic tilt will be conntected with navigation and robotic systems for total hip arthroplasty. Along with intraoperative data a patientindividual optimized implant position can be achieved.

Offset restoration in total hip arthroplasty (THA) is associated with postoperative range of motion (ROM) and gait kinematics. We aimed to research into the impact of high offset (HO) and standard stems on postoperative ROM. 121 patients received cementless THA through a minimally-invasive anterolateral approach. A 360° hip ROM analysis software calculated impingement-free hip movement based on postoperative 3D-CTs compared to ROM values necessary for activities of daily living (ADL). The same model was then run a second time after changing the stem geometry between standard and HO configuration with the implants in the same position. HO stems showed higher ROM for all directions between 4.6 and 8.9° (p 0.03). Patient-individual restoration of offset is crucial for free ROM in THA. Both over and underrestoration of offset should be avoided.

The modern cementing technique in cemented arthroplasty is a highly standardized and, therefore, safe procedure. Nevertheless, aseptic loosening is still the main reason for revision after cemented total knee or cemented total hip arthroplasty. To investigate whether an additional carbon dioxide lavage after a high-pressure pulsatile saline lavage has a positive effect on the bone–cement interface or cement penetration, we set up a standardized laboratory experiment with 28 human femoral heads. After a standardized cleaning procedure, the test implants were cemented onto the cancellous bone. Subsequently, the maximum failure load of the bone–cement interface was determined using a material testing machine to pull off the implant, and the cement penetration was determined using computed tomography. Neither the maximum failure load nor cement penetration into the cancellous bone revealed significant differences between the groups. In conclusion, according to our experiments, the additive use of the carbon dioxide lavage after the high-pressure pulsatile lavage has no additional benefit for the cleaning of the cancellous bone and, therefore, cannot be recommended without restrictions.

In der postoperativen Rontgenkontrolle nach Huft-TEP-Implantation erfolgt durch die Bestimmung der Komponentenstellung eine objektivierbare Qualitatskontrolle. Die Pfannenposition wird hierbei durch die Steilheit und die Drehung nach vorne beschrieben. Zwischen den radiographisch gemessenen Werten und der tatsachlichen (anatomischen) Pfannenstellung besteht jedoch eine Diskrepanz, die zu Fehlinterpretationen fuhren kann. Um die Diskrepanz zwischen tatsachlicher und radiographisch vermessener Pfannenstellung bildlich darzustellen, wurde in dem Video ein Pfannenhalter verwendet, an dem die Drehung nach vorne und die Pfannensteilheit winkelgenau eingestellt werden kann. Hierdurch kann die Pfannenposition (Anteversion und Inklination) in der radiographischen und anatomischen Definition naher erlautert werden. Der Zuschauer soll einen Eindruck bekommen, ab wann die radiologisch gemessenen Werte nur mit groser Vorsicht zu betrachten sind. In dem Video zeigt sich in der simulierten Rontgen- und Bildsequenz, dass bei gleichbleibender tatsachlicher Pfannensteilheit am Modell mit zunehmender Anteversion uber 20° die Inklination radiographisch flacher gemessen wird. Alleiniges Betrachten der radiographischen Winkelwerte der Anteversion und Inklination kann zu Fehlinterpretationen der tatsachlichen Pfannenstellung fuhren. In bildlicher Darstellung zeigen wir, dass eine unterschiedliche Pfannensteilheit und -drehung anhand der radiographischen Messwerte nicht sicher erkannt werden kann. Die wahre Pfannenposition in der anatomischen Definition lasst sich aus der radiographischen Position errechnen. Hierzu mussen jedoch beide Pfannenwerte (rad. Anteversion und rad. Inklination) berucksichtigt werden.

Background Computed tomography (CT) is the gold standard for the accurate measurement of cup inclination and anteversion in total hip arthroplasty (THA). However, functional cup position strongly depends on the tilt of the pelvis and thus pelvic tilt in the supine position on the CT table harbors the risk of misinterpretation. Purpose To evaluate the influence of pelvic tilt on cup measurements in postoperative CT scans. Material and Methods This is a secondary outcome analysis of a prospective study. In 123 patients undergoing THA, anatomic cup inclination and anteversion as measured on postoperative 3D-CT scans were compared between: (i) the anterior pelvic plane (APP) resembling neutral pelvic tilt; and (ii) the coronal plane representing the standard planes on CT. Furthermore, the effect of the variation on cup positions within Lewinnek’s safe zone in relation to the applied reference plane was assessed. Results Mean pelvic tilt in supine position was –3.5° ± 5.6°. This resulted in a mean difference for anteversion between APP und coronal plane of 2.1° ± 3.7° and of 2.1° ± 1.9° for cup inclination, respectively. The change varied up to 20.2° for cup inclination and up 12.2° for cup anteversion. The overall conversion rate for inclination and/or anteversion regarding Lewinnek’s safe zone was high at 23.6% (29/123). Conclusion Pelvic tilt affects cup orientation on CT scans depending on the applied reference plane. Standard CT planes should be corrected regarding pelvic tilt before measurements to avoid errors in measurement.

Introduction The Hospital Frailty Risk Score (HFRS) is a validated risk stratification model referring to the cumulative deficits model of frailty. The purpose of this study was to evaluate the HFRS as a predictor of 90-day readmission and complications after revision total hip (rTHA) and knee (rTKA) arthroplasty. Methods In a retrospective analysis of 565 patients who had undergone rTHA or rTKA between 2011 and 2019, the HFRS was calculated for each patient. Rates of adverse events were compared between patients with low and intermediate or high frailty risk. Multivariable logistic regression models were used to assess the relationship between the HFRS and post-operative adverse events. Results Patients with intermediate or high frailty risk showed higher rates of readmission (30days: 23.8% vs. 9.9%, p = 0.006; 90days: 26.2% vs. 13.0%, p < 0.018), surgical complications (28.6% vs. 7.8%, p < 0.001), medical complications (11.9% vs. 1.0%, p < 0.001), other complications (28.6% vs. 2.3%, p < 0.001), Clavien-Dindo grade IV complications (14.3% vs. 4.8%, p = 0.009), and transfusion (33.3% vs. 6.1%, p < 0.001). Multivariable logistic regression analyses revealed a high HFRS as independent risk factor for surgical complications (OR = 3.45, 95% CI 1.45-8.18, p = 0.005), medical complications (OR = 7.29, 95% CI 1.72-30.97, p = 0.007), and other complications (OR = 14.15, 95% CI 5.16-38.77, p < 0.001). Conclusion The HFRS predicts adverse events after rTHA and rTKA. As it derives from routinely collected data, the HFRS could be implemented automated in hospital information systems to facilitate identification of at-risk patients.

Background and purpose ��� Improving health care and demographic change have resulted in a steady increase in geriatric patients undergoing total hip (THA) and knee (TKA) arthroplasty. Postoperative delirium (POD) is a frequent and severe complication after major surgery. Therefore, we analyzed the impact of POD on outcome after THA and TKA. Patients and methods ��� In a consecutive series of 10,140 patients who had undergone elective THA or TKA between 2011 and 2020, rates of reoperation within 90 days, readmission within 90 days, complications, and responder rate as defined by the OMERACT-OARSI criteria were compared between patients with and without POD. Multivariable logistic regression models were used to assess the relationship between POD and other postoperative complications. Results ��� Patients with POD showed higher rates of reoperation (12% vs. 5%), readmission (15% vs. 5%), surgical complications (7% vs. 2%), non-surgical complications (8% vs. 4%), Clavien���Dindo IV�� complications (10% vs. 2%) and transfusion (14% vs. 2%). POD led to lower responder rate (76% vs. 87%) 1 year after total joint replacement. All previous comparisons statistically significant. Multivariable logistic regression analyses revealed POD as an independent risk factor for reoperation (OR = 2; CI 1���3), readmission (OR = 2; CI 2���4) and Clavien���Dindo IV�� complications (OR = 3; CI 2���5). Interpretation ��� POD is a serious problem in elective joint replacement. Affected patients suffer more complications and show poor patient-reported outcome 1 year postoperatively. Systematic prevention strategies and standardized therapy protocols are mandatory to avoid burden to patients and healthcare providers.

Introduction Because of the ongoing discussion of imageless navigation in total knee arthroplasty (TKA), its advantages and disadvantages were evaluated in a large patient cohort. Methods This retrospective analysis included 2464 patients who had undergone TKA at a high-volume university arthroplasty center between 2012 and 2017. Navigated and conventional TKA were compared regarding postoperative mechanical axis, surgery duration, complication rates, one-year postoperative patient-reported outcome measures (PROMs) (WOMAC and EQ-5D indices), and responder rates as defined by the criteria of the Outcome Measures in Rheumatology and Osteoarthritis Research Society International consensus (OMERACT-OARSI). Results Both navigated (1.8 ± 1.6°) and conventional TKA (2.1 ± 1.6°, p = 0.002) enabled the exact reconstruction of mechanical axis. Surgery duration was six minutes longer for navigated TKA than for conventional TKA (p p = 0.39), joint infection (p = 0.42 and thromboembolic events (p = 0.03). Periprosthetic fractures occurred more frequently during conventional TKA (p = 0.001). One-year PROMs showed excellent improvement in both groups. The WOMAC index was statistically higher for navigated TKA than for conventional TKA (74.7 ± 19.0 vs. 71.7 ± 20.7, p = 0.014), but the increase was not clinically relevant. Both groups had a similarly high EQ-5D index (0.23 ± 0.24 vs. 0.26 ± 0.25, p = 0.11) and responder rate (86.5% [256/296] vs. 85.9% [981/1142], p = 0.92). Conclusion Both methods enable accurate postoperative leg alignment with low complication rates and equally successful PROMs and responder rates one year postoperatively. Level of evidence III. Retrospective cohort study.

Models for risk stratification and prediction of outcome, such as the Charlson Comorbidity Index (CCI), the Elixhauser Comorbidity Method (ECM), the 5-factor modified Frailty Index (mFI-5), and the Hospital Frailty Risk Score (HFRS) have been validated in orthopedic surgery. The aim of this study is to compare the predictive power of these models in total hip and knee replacement.In a retrospective analysis of 8250 patients who had undergone total joint replacement between 2011 and 2019, CCI, ECM, mFI-5, and HFRS were calculated for each patient. Receiver operating characteristic curve plots were generated and the area under the curve (AUC) was compared between each score with regard to adverse events such as transfusion, surgical, medical, and other complications. Multivariate logistic regression models were used to assess the relationship among risk stratification models, demographic factors, and postoperative adverse events.In prediction of surgical complications, HFRS performed best (AUC: 0.719, P.001), followed by ECM (AUC: 0.578, P.001), mFI-5 (AUC: 0.564, P = .003), and CCI (AUC: 0.555, P = .012). With regard to medical complications, other complications, and transfusion, HFRS also was superior to ECM, mFI-5, and CCI. Multivariate logistic regression analyses revealed HFRS as an independent risk stratification model associated with all captured adverse events (P ≤ .001).The HFRS is superior to current risk stratification models in the context of total joint replacement. As the HRFS derives from routinely collected administrative data, healthcare providers can identify at-risk patients without additional effort or expense.

The Hospital Frailty Risk Score (HFRS) is a validated geriatric comorbidity measure derived from routinely collected administrative data. The purpose of this study is to evaluate the utility of the HFRS as a predictor for postoperative adverse events after primary total hip (THA) and knee (TKA) arthroplasty.In a retrospective analysis of 8250 patients who had undergone THA or TKA between 2011 and 2019, the HFRS was calculated for each patient. Reoperation rates, readmission rates, complication rates, and transfusion rates were compared between patients with low and intermediate or high frailty risk. Multivariate logistic regression models were used to assess the relationship between the HFRS and postoperative adverse events.Patients with intermediate or high frailty risk showed a higher rate of reoperation (10.6% vs 4.1%, P.001), readmission (9.6% vs 4.3%, P.001), surgical complications (9.1% vs 1.8%, P.001), internal complications (7.3% vs 1.1%, P.001), other complications (24.4% vs 2.0%, P.001), Clavien-Dindo grade IV complications (4.1% vs 1.5%, P.001), and transfusion (10.4% vs 1.3%, P.001). Multivariate logistic regression analyses revealed a high HFRS as independent risk factor for reoperation (odds ratio [OR] = 2.1; 95% confidence interval [CI], 1.46-3.09; P.001), readmission (OR = 1.78; 95% CI, 1.21-2.61; P = .003), internal complications (OR = 3.72; 95% CI, 2.28-6.08; P.001), surgical complications (OR = 3.74; 95% CI, 2.41-5.82; P.001), and other complications (OR = 9.00; 95% CI, 6.58-12.32; P.001).The HFRS predicts adverse events after THA and TKA. As it derives from routinely collected data, the HFRS enables hospitals to identify at-risk patients without extra effort or expense.Level III-retrospective cohort study.

Purpose Valgus deformity presents a particular challenge in total knee arthroplasty. This condition regularly leads to contractures of the lateral capsular ligament complex and to overstretching of the medial ligamentous complex. Reconstruction of the knee joint kinematics and anatomy often requires lateral release. However, data on how such release weakens the stability of the knee are missing in the literature. This study investigated the effects of sequential lateral release on the collateral stability of the ligament complex of the knee in vitro. Methods Ten knee prostheses were implanted in 10 healthy cadaveric knee joints using a navigation device. Soft tissue lateral release consisted of five release steps, and stiffness and stability were determined at 0, 30, 60 and 90° flexion after each step. Results Soft tissue lateral release increasingly weakened the ligament complex of the lateral compartment. Because of the large muscular parts, the release of the iliotibial band and the M. popliteus had little effect on the stability of the lateral and medial compartment, but release of the lateral ligament significantly decreased the stability in the lateral compartment over the entire range of motion. Stability in the medial compartment was hardly affected. Conversely, further release of the posterolateral capsule and the posterior cruciate ligament led to the loss of stability in the lateral compartment only in deep flexion, whereas stability decreased significantly in the medial compartment. Conclusion Our study shows for the first time the association between sequential lateral release and stability of the ligamentous complex of the knee. To maintain the stability, knee surgeons should avoid releasing the entire lateral collateral ligament, which would significantly decrease stability in the lateral compartment.

Restoration of biomechanics is crucial in total hip arthroplasty, in order to ensure a free postoperative range of motion for activities of daily life. Failure may result in impingement and thus instability, limping and finally patient dissatisfaction. In daily practice, preoperative templating is usually performed on magnification-corrected, plain radiographs of the hip. Due to the divergence of the X-ray beams and the position of the pelvis in relation to the film, measurements on plain radiographs are susceptible to error. Whereas leg length measurements are highly accurate, femoral offset is frequently underestimated on plain radiographs. The benchmark for acceptable postoperative leg length and offset differences is still under debate in the literature. However, discrepancies of 1 cm in relation to the non-affected, contralateral side should not be exceeded. Gait analysis is able to detect even differences in leg length and offset above 5 mm due to altered gait kinematics. For intraoperative control of leg length and offset, a variety of different methods have been described in the literature. Beside alignment guides, rulers and other tools, intraoperative fluoroscopy and computer-guided navigation allow the surgeon to intraoperatively analyse leg length and offset changes. Both techniques show high accuracy, although the precision is higher for navigation with a reduced number of outliers. For measurement of stem torsion, computed tomography is the gold standard. However, stem torsion can also be evaluated on plain hip radiographs by measuring the projected prosthetic neck-stem angle. Native femoral anteversion can be assessed by the size of the lesser trochanter. Since the version of the femoral stem can highly vary from the native femoral anteversion, the Isthmus Ratio (iRatio) - the relationship between canal isthmus and calcar isthmus in the anteroposterior and Lauenstein view - helps to predict the torsion of the final intraoperative stem.Eine exakte Rekonstruktion der Biomechanik ist ein wesentlicher Bestandteil in der Hüftendoprothetik für eine gute postoperative Beweglichkeit und Stabilität des Kunstgelenks. Die präoperative Planung des Beinlängen- und Offsetausgleichs wird üblicherweise auf größenskalierten konventionellen Röntgenbildern durchgeführt, die jedoch durch die zweidimensionale Projektion der Gefahr von Fehlberechnungen unterliegen. Insbesondere das femorale Offset wird dabei häufig unterschätzt. Bei der Rekonstruktionsgenauigkeit von Beinlänge und Offset sollten Unterschiede von über 1 cm postoperativ vermieden werden. Analysen der Gangkinematik zeigen jedoch bereits Veränderungen im Gangmuster bei Beinlängen- und Offsetunterschieden von über 5 mm. Neben einer Vielzahl anderer Methoden eignen sich zur intraoperativen Umsetzung der Beinlängen- und Offsetrekonstruktion sowohl die bildfreie Navigation als auch die Fluoroskopie. Eine Abschätzung der Schafttorsion der einliegenden Endoprothese ist neben des Goldstandards CT auch auf konventionellen Röntgenaufnahmen mithilfe der Bestimmung des projizierten CCD-Winkels möglich. Als prädiktiver Parameter eignet sich die Isthmus-Ratio (iRatio), um bereits präoperativ nativradiologisch einen Hinweis der intraoperativ zu erwartenden Schafttorsion zu erhalten. Die Größe des Trochanter minor hilft, eine Abschätzung der nativen Torsion des Femurs treffen zu können.

In revision hip arthroplasty, custom-made implants are one option in patients with acetabular Paprosky III defects. In a retrospective analysis, we identified 11 patients undergoing cup revision using a custom-made implant. The accuracy of the intended position of the implant was assessed on post-operative 3D CT and compared to the pre-operative 3D planning in terms of inclination, anteversion, and centre of rotation. In addition, the accuracy of post-operative plain radiographs for measuring implant position was evaluated in relation to the 3D CT standard. We found a mean deviation between the planned and the final position of the custom-made acetabular implant on 3D CT of 3.6° ± 2.8° for inclination and of − 1.2° ± 7.0° for anteversion, respectively. Restoration of center of rotation succeeded with an accuracy of 0.3 mm ± 3.9 mm in the mediolateral (x) direction, − 1.1 mm ± 3.8 mm in the anteroposterior (y) direction, and 0.4 mm ± 3.2 mm in the craniocaudal (z) direction. The accuracy of the post-operative plain radiographs in measuring the position of the custom-made implant in relation to 3D CT was 1.1° ± 1.7° for implant inclination, − 2.6° ± 1.3° for anteversion and 1.3 mm ± 3.5 mm in the x-direction, and − 0.9 mm ± 3.8 mm in the z-direction for centre of rotation. Custom-made acetabular implants can be positioned with good accuracy in Paprosky III defects according to the pre-operative planning. Plain radiographs are adequate for assessing implant position in routine follow-up.

Total hip and knee replacements are frequently performed curative treatment options in end-stage arthritis. In this study, we analyzed clinical outcome, complications, and predictors of outcome in modern joint replacement.In a retrospective analysis of over 2000 primary total hip and knee replacements from our institutional joint registry, responder rates for positive outcome as defined by the OMERACT-OARSI criteria, postoperative complication rates, and patient-reported outcome measures (EQ-5D, WOMAC) within the first year were compared between hip and knee replacements. Furthermore, preoperative risk factors associated with nonresponder rate were evaluated.Positive responder rate was higher for hip replacements with 92.8% (1145/1234) than for knee replacements with 86.1% (839/975, P.001). Infection rates were lower (P = .04), whereas intraoperative fracture occurred more frequently (P = .001) in hip than in knee replacements. Patient-reported outcome measures 1 year after surgery were higher in hip than in knee replacements with EQ-5D (0.88 ± 0.17 to 0.81 ± 0.19, P.001) and WOMAC (84.58 ± 16.73 to 74.31 ± 18.94, P.001). Besides the type of joint replacement (hazard ratio [HR] 2.0, P.001), high preoperative outcome measures (HR 7.4, P.001) and male gender (HR 1.4, P = .05) were independent risk factors of nonresponders after joint replacement.Both total hip and knee replacements are safe procedures with low complication rates. Still, postoperative outcome is higher in hip than in knee arthroplasty. High preoperative clinical scores are a risk factor for poor clinical improvement following total joint replacement and can be used in counseling patients in the office.

Der Ansturm auf das Medizinstudium ist ungebrochen. Allein im Wintersemester 2016 gab es fur 9150 Studienplatze in Deutschland uber 43.800 Bewerber. Einer der Kernpunkte im „Masterplan 2020“ ist die Reform der Lehre an den medizinischen Fakultaten. Studierende der Humanmedizin werden demnach zukunftig primar auf Grundlage kompetenzorientierter, integrierter Curricula ausgebildet werden. Der vorliegende Beitrag soll Sie mit modernen Lehrkonzepten/-methoden und mit aktuellen Prufungsformaten vertraut machen, die in der studentischen Ausbildung in Orthopadie und Unfallchirurgie eine besondere Rolle spielen. Die Vermittlung von arztlichen und evidenzbasierten Handlungskompetenzen, klinischen Untersuchungstechniken, diagnostischen/therapeutischen Verfahren und hygienisches Arbeiten sind dabei besonders wichtig. Krankheitsbezogene, kompetenzorientiert formulierte Lernziele und Prufungsformate sollen den Studierenden helfen, die Tiefe des Fachs zu erfassen.

Our aim was to compare the long-term outcome between navigated and conventional total knee arthroplasty (TKA), which is currently not known. Long-term survivorship, clinical scores and radiographic results of a matched-pair group of 350 patients (350 knees) treated with navigated (n = 157) or conventional (n = 188) TKA for osteoarthritis over a period of 11 years were reviewed retrospectively. The mean clinical follow-up was ten years. There were no clinically relevant differences with respect to any clinical outcome, patient satisfaction or pain between the two groups. Coronal leg alignment was closer (1.7-3.1°) to the neutral mechanical axis in the navigated group compared with the conventional group (2.6-4.7°). A total of 12 knees (6.4%) in the conventional group and three (1.9%) in the navigated group underwent revision surgery (p = 0.04), resulting in an absolute risk reduction of 4.5% for revision surgery by using navigation. Using any revision as an end point, the ten-year Kaplan-Meier survivorship was 98.1% in the navigated and 92.5% in the conventional group. Navigated TKA improves implant survivorship compared with conventional TKA.

Background The estimation of femoral version in preoperative planning of total hip arthroplasty and to assess complications after total hip arthroplasty is crucial. Recent studies have recommended the posterior lesser trochanter line as an intraoperative reference for estimating femoral version. We hypothesized, that if there is a correlation, the posterior lesser trochanter line could be used to assess femoral version in computed tomography (CT) scans. Purpose To evaluate the correlation between the posterior lesser trochanter line and the posterior femoral condyle axis. Material and Methods CT scans of 126 patients after unilateral total hip arthroplasty were analyzed by means of a newly developed digital planning software for CT scans. Both hips were measured, the angle between the posterior lesser trochanter line and the posterior femoral condyle axis was determined, and the relationship between both lines was evaluated. Results We found significant differences between male and female patients ( P Conclusion There is no reliable correlation between posterior lesser trochanter line and posterior femoral condyle axis. Therefore, posterior lesser trochanter line should not be used to assess femoral version in CT scans. As a consequence, the gold standard for measuring femoral version should still be a three-dimensional CT scan of the whole femur.

Gemas der demografischen Entwicklung nimmt der Anteil der endoprothetischen Versorgungen am Kniegelenk bei alteren Menschen zu. Es erfolgte eine Analyse zu der speziellen Situation beim alteren Menschen, alternativen Therapieoptionen, perioperativen Risiken, praoperativer Vorbereitung, intraoperativen Besonderheiten und Outcome. Die gegenwartige wissenschaftliche Datenlage wurde ausgewertet und die eigenen wissenschaftlichen Studienergebnisse werden prasentiert. Altere Menschen haben ein erhohtes perioperatives Risiko beim kunstlichen Kniegelenkersatz. Eine grundliche interdisziplinare Vorbereitung ist erforderlich, um Risiken zu reduzieren. Die Stabilitat des Kapselbandapparates nimmt mit zunehmenden Alter nicht ab. Das postoperative Ergebnis nach kunstlichen Kniegelenkersatz wird bei alteren Menschen von der praoperativen Funktion und psychosozialen Faktoren entscheidend beeinflusst. Der kunstliche Kniegelenkersatz beim alteren Menschen ist eine besondere Herausforderung fur den orthopadischen Chirurgen und bedarf einer engen interdisziplinaren Zusammenarbeit.

In this prospective study of 66 patients undergoing cementless total hip arthroplasty through a minimally invasive anterolateral approach, we evaluated the impact of an intraoperative hybrid combined anteversion technique on postoperative range of motion (ROM).After navigation of femoral stem anteversion, trial acetabular components were positioned manually, and their position recorded with navigation. Then, final components were implanted with navigation at the goals prescribed by the femur-first impingement detection algorithm. Postoperatively, three-dimensional computed tomographies were performed to determine achieved component position and model impingement-free ROM by virtual hip movement, which was compared with published values necessary for activities of daily living. This model was run a second time with the implants in the position selected by the surgeon rather than the navigation program. In addition, we researched into risk factors for ROM differences between the freehand and navigated cup position.We found a lower flexion of 8.3° (8.8°, P.001) and lower internal rotation of 9.2° (9.5°, P.001) for the freehand implanted cups in contrast to a higher extension of 9.8° (11.8°, P.001) compared with the navigation-guided technique. For activities of daily living, 58.9% (33/56) in the freehand group compared with 85.7% (48/56) in the navigation group showed free flexion (P.001) and similarly 50.0% (28/56) compared with 76.8% (43/56) free internal rotation (P.001). Body mass index, incision length, and cup size were identified as independent risk factors for reduced flexion and internal rotation in the freehand group.For implementation of a combined anteversion algorithm, intraoperative alignment guides for accurate cup positioning are required using a minimally invasive anterolateral approach. Obese patients are especially at risk of cup malpositioning.

We aimed to investigate the relationship between postoperative leg length/offset (LL/OS) reconstruction and gait performance after total hip arthroplasty (THA). In the course of a prospective randomized controlled trial, 60 patients with unilateral hip arthrosis received cementless THA through a minimally-invasive anterolateral surgical approach. One year post-operatively, LL and global OS restoration were analyzed and compared to the contralateral hip on AP pelvic radiographs. The combined postoperative limb length/OS reconstruction of the operated hip was categorized as restored (within 5mm) or non-restored (more than 5mm reduction or more than 5mm increment). The acetabular component inclination, anteversion and femoral component anteversion were evaluated using CT scans of the pelvis and the femur. 3D gait analysis of the lower extremity and patient related outcome measures (HHS, HOOS, EQ-5D) were obtained pre-operatively, six months and twelve months post-operatively by an observer blinded to radiographic results. Component position of cup and stem was comparable between the restored and non-restored group. Combined LL and OS restoration within 5mm resulted in higher Froude number (p

Die Dyskinesie der Patella stellt ein relevantes Problem nach primarer Knietotalendoprothetik dar. Die Patellanavigation ermoglicht die Darstellung der Patellakinematik intraoperativ in Echtzeit bei dynamischer Untersuchung. In dem Videobeitrag wird die Technik der Patellanavigation bei der Knietotalendoprothetik demonstriert und eine mogliche Konsequenz der Messung dargestellt. Im berichteten Fall zeigt sich nach Implantation ein vermehrter lateraler Tilt nach Implantation der Knietotalendoprothese. Durch eine laterale Retinakulumerweiterungsplastik kann der vermehrte Tilt reduziert werden. In ausgewahlten Fallen ist die Patellanavigation geeignet, die Kinematik der Patella intraoperativ vor und nach Prothesenimplantation zu messen. Intraoperativ konnen dann noch Modifikationen der Implantatpositionierung oder erganzende Weichteileingriffe eine patellofemorale Dyskinesie verhindern.

Various methods are available for measuring acetabular cup position after total hip arthroplasty (THA) on standard anterior-posterior (AP) radiographs. We compared the accuracy of a commercial radiographic planning software program with that of three-dimensional computed tomography (3D-CT) scans. We obtained plain AP radiographs and 3D-CTs from 65 patients after THA. In addition to calculating cup anteversion and inclination with 3D-CT, we determined the cup position using the radiographic planning software program mediCAD® 2.5 (Hectec, Niederviehbach, Germany). Furthermore, we compared the measurements using the inter-teardrop and bi-ischial lines as pelvic landmarks. The mean difference in anteversion between 3D-CT and mediCAD® software was 0.1° using the inter-teardrop line (standard deviation [SD], 8.8°; range, −21° to 23°; p = 0.97) and 0.4° using the bi-ischial line (SD, 8.8°; range, −23° to 21°; p = 0.72). Inclination showed a mean difference of 0.6° using the inter-teardrop line (SD, 4.4°; range, −9° to 21°; p = 0.24) and 0.5° using bi-ischial line (SD, 4.6°; range, −9° to 22°; p = 0.35). The means for absolute differences were 7.2° for anteversion and 3.1° for inclination. With regard to using the bi-ischial or inter-teardrop line, no significant difference was found between the two pelvic landmarks. The intra-class correlation coefficient (ICC) was analysed for anteversion and inclination using either the inter-teardrop line or the bi-ischial line as radiographic baseline. A radiographic planning software program (mediCAD®) is a helpful tool for measuring cup inclination on AP radiographs. With respect to anteversion, measurements are rather susceptible to mistakes with mean inaccuracies of over 7°. Thus, 3D-CT remains the “gold standard” if a lower tolerance limit (±3°) is required for more complex biomechanical evaluations. As a pelvic landmark, the interteardrop line is preferential to the bi-ischial line because of its lower impact on the position of the pelvis.

Generally range of motion (ROM) in total hip arthroplasty (THA) is intraoperatively assessed by eye. Can we assume that visual estimation of ROM is reliable? 60 patients underwent cementless THA in a subgroup analysis of a clinical prospective trial using a minimally invasive anterolateral approach in lateral decubitus position. Four experienced surgeons intraoperatively estimated ROM visually by assessment of the femur relative to the alignment of the patient’s pelvis. These estimations were compared with computer navigation measurements. We found a mean difference between navigation measurements and intraoperative estimations by eye of −5.6° (±10.9°; −17° to 30°) for flexion, respectively, −0.4° (±10.7°; −24° to 30°) for extension, 8.7° (±9.0°; −10° to 34°) for abduction, 5.9° (±18.3°; −58° to 68°) for external rotation and −5.8° (±12.1°; −38° to 22°) for internal rotation. Multivariate analysis showed no association between the visual accuracy of estimation of ROM and patient characteristics, such as BMI, sex, grade of osteoarthritis and treatment side except for a significant correlation of visual accuracy of estimation of extension and the level of professional experience. Otherwise, the level of professional experience had no impact on the accuracy of estimation of ROM by eye. Even the experienced surgeon’s intraoperative estimation of ROM by eye is not reliable and differs up to 30° compared to objective measurements in minimally invasive THA. For accurate intraoperative assessment of ROM, the use of technical devices is recommended. DRKS00000739.

Correct assessment of femoral stem torsion is crucial in total hip arthroplasty (THA). In this study, we aimed to compare a recently published novel method based on anteroposterior (AP) hip radiographs using the projected caput-collum-diaphyseal (CCD) angle (AP CCD) with the modified posteroanterior Budin view.AP radiographs, modified Budin views, and 3-dimensional computed tomography (3D-CT) images were obtained in 30 patients after minimally invasive, cementless THA. Radiographic measurements performed by 4 observers twice in a 6-week interval were compared with 3D-CT measurements. Furthermore, correlations between the radiographic deviation to 3D-CT and patient specific characteristics were evaluated.We found a mean difference of 2.2 ± 6.8° between AP CCD and 3D-CT measurements of femoral stem torsion and -0.5 ± 4.2° between the modified Budin view and 3D-CT. We found a high correlation between mean radiographic and 3D-CT stem torsion (r = 0.78, P.001 for AP CCD and r = 0.84, P.001 for Budin view). The observers had excellent agreements within (intraclass correlation coefficient, ≥0.88 for AP CCD and intraclass correlation coefficient, ≥0.94 for Budin view) and between (mean concordance correlation coefficient, ≥0.79 for AP CCD and concordance correlation coefficient, ≥0.86 for Budin view) their radiographic measurements.Both radiographic methods enable a simple orientation and a practical conventional radiographic estimation of stem torsion on hip radiographs after THA. However, CT remains the golden standard for exact estimation of stem torsion.

The aim of this prospective study is to validate a vector arithmetic method for measuring acetabular cup orientation after total hip arthroplasty (THA) and to verify the clinical practice.We measured cup anteversion and inclination of 123 patients after cementless primary THA twice by two examiners on AP pelvic radiographs with a vector arithmetic method and compared with a 3D-CT based reconstruction model within the same radiographic coronal plane.The mean difference between the radiographic and the 3D-CT measurements was - 1.4° ± 3.9° for inclination and 0.8°± 7.9° for anteversion with excellent correlation for inclination (r = 0.81, p 0.001) and moderate correlation for anteversion (r = 0.65, p 0.001). The intraclass correlation coefficient for measurements on radiographs ranged from 0.98 (95 %-CI: 0.98; 0.99) for the first observer to 0.94 (95 %-CI: 0.92; 0.96) for the second observer. The interrater reliability was 0.96 (95 %-CI: 0.93; 0.98) for inclination and 0.93 (95 %-CI: 0.85; 0.96) for anteversion.The largest errors in measurements were associated with an extraordinary pelvic tilt. In order to get a valuable measurement for measuring cup position after THA on pelvic radiographs by this vector arithmetic method, there is a need for a correct postoperative ap view, with special regards to the pelvic tilt for the future.• Measuring acetabular cup orientation on anteroposterior radiographs of the hip after THA is a helpful procedure in everyday clinical practice as a first-line imaging modality• CT remains the golden standard to accurately determine acetabular cup position.• Future measuring on radiographs for cup orientation after THA should account for integration of the pelvic tilt in order to maximize the measurement accuracy. Citation Format: • Craiovan B, Weber M, Worlicek M et al. Measuring Acetabular Cup Orientation on Antero-Posterior Radiographs of the Hip after Total Hip Arthroplasty with a Vector Arithmetic Radiological Method. Is It Valid and Verified for Daily Clinical Practice?. Fortschr Röntgenstr 2016; 188: 574 - 581.

Preoperative knowledge of femoral stem anteversion can reduce instability and impingement especially using the standard "cup first" technique in cementless total hip arthroplasty (THA). In this study, we asked whether stems at risk of retroversion or high anteversion (>20°) can be detected preoperatively using hip radiographs in two planes (anteroposterior and Lauenstein). In 123 patients undergoing cementless THA using a non-anatomic, non-modular, straight stem, low centered hip radiographs in two planes were obtained preoperatively and three-dimensional computed tomography (3D-CT) 6 week postoperatively. The novel developed Isthmus Ratio (iRatio) as the relation between canal isthmus and calcar isthmus in the anteroposterior and Lauenstein view was calculated by two observers twice in a 6-week interval. iRatio was compared to postoperative 3D-CT stem version measured by an independent and blinded, external institute. We found a correlation between mean radiographic iRatio and 3D-CT stem torsion of r = 0.578 (p

The purpose of this study was to investigate the effects of sequential medial release on the stiffness and collateral stability of the ligament complex of the knee. Irrespective of the implantation technique used, varus deformity frequently requires release of the capsular ligament complex. Yet, no data are available on how stiffness and stability of the knee ligament complex are weakened by such release. After total knee arthroplasty, ten healthy Thiel-fixed knee joints were subjected to sequential medial release consisting of six release steps. After each step, stiffness and stability were determined at 0°, 30°, 60°, and 90°. Sequential medial release increasingly weakened the ligament complex. In extension, release of the anteromedial tibial sleeve 4 cm below the joint line already weakened the ligament complex by approximately 13%. Release 6 cm below the joint line reduced stiffness and stability by 15–20% over the entire range of motion. After detachment of the medial collateral ligament, stability was only about 60% of its initial value. Our study showed for the first time the association between medial release and stiffness and stability of the knee ligament complex. To maintain stability, vigorous detachment of the knee ligament complex should be avoided. Release of the anteromedial tibial sleeve already initiates loss of stability. The main stabiliser is the medial ligament, which should never be completely detached. IV.

A prospective randomized controlled trial is presented that is used to compare gait performance between the computer assisted Femur First (CAS FF) operation method and conventional THR (CON). 60 patients underwent a 3D gait analysis of the lower extremity at pre-operative, 6 months post-operative and twelve months post-operative.Detailed verification experiments were facilitated to ensure the quality of data as well as to avoid over-interpreting of the data. The results confirm a similar data-quality as reported in the literature. Walking speed, range of motion and symmetry thereof improved over the follow-up period, without significant differences between the groups. While all parameters do significantly increase over the follow-up period for both groups, there were no significant differences between them at any given time-point. Patients undergoing CAS FF showed a trend to improved hip flexion angle indicating a possible long-term benefit. (C) 2016 Elsevier B.V. All rights reserved.

BackgroundTotal hip arthroplasty (THA) could be associated with a higher failure rate in patients after osteonecrosis of the femoral head (ONFH) compared to a patient population with primary osteoarthritis prior THA, especially regarding the acetabular component. One major reason could be the compromised acetabular bone quality. Therefore, we performed a retrospective case matched study to assess: 1) Is there a difference in periprosthetic bone mineral density between patients with an ONFH prior THA and controls? 2) Do patients with an ONFH prior THA have a lower bone mineral density compared to controls? 3) Which region in the periprosthetic bone stock is more likely to present differences in periprosthetic bone mineral density between both groups?HypothesisWe hypothesized that there is a poorer bone mineral density (BMD) in the periacetabular bone stock in patients with an ONFH prior THA compared to controls receiving a THA due to primary osteoarthritis.Patients and methodsWe compared the BMD of 50patients with ONFH to 50controls with primary osteoarthritis prior THA using the same implant in mean 5years after surgery by means of dual energy X-ray absorptiometry (DXA). We analysed 3acetabular ROIs according to DeLee and Charnley in a modified measurement technique.ResultsIn ROI 3, representing acetabulum's upper aspect, statistically significant lower BMD values for the ONFH group could be found (P

Different target areas within the concept of combined cup and stem anteversion have been published for total hip arthroplasty (THA). We asked whether component positioning according to eight standard combined anteversion rules is associated with (1) more physiological gait patterns, (2) higher improvement of gait variables and (3) better clinical outcome after THA. In a prospective clinical study, 60 patients received cementless THA through an anterolateral MIS approach in a lateral decubitus position. Six weeks postoperatively, implant position was analysed using 3D-CT by an independent external institute. Preoperatively, six and 12 months postoperatively range of motion, normalized walking speed and hip flexion symmetry index were measured using 3D motion-capture gait analysis. Patient-related outcome measures (HHS, HOOS, EQ-5D) were obtained by an observer blinded to 3D-CT results. Eight combined anteversion definitions and Lewinnek’s “safe zone” were evaluated regarding their impact on gait patterns and clinical outcome. Combined cup and stem anteversion according to standard combined anteversion definitions as well as cup placement within Lewinnek’s “safe zone” did not influence range of motion, normalized walking speed and/or hip flexion symmetry index six and 12 months after THA. Similarly, increase of gait parameters within the first year after THA was comparable between all eight combined anteversion rules. Clinical outcome measures like HHS, HOOS and EQ-5D did not show any benefit for either of the combined anteversion definitions. Standard combined cup and stem anteversion rules do not improve postoperative outcome as measured by gait analysis and clinical scores within one year after THA.

Heterotopic ossification (HO) after THA can lead to pain, impaired range of motion and possibly revision surgery. This article summarizes current literature on the pathogenesis of HO in THA and trauma. Second, it presents the results of a survey on prophylactic concepts for HO in Germany. A narrative literature review was conducted by searching three databases (Pubmed, ScienceDirect, the Cochrane library) on the aetiology of HO. Between 2013 and 2014, a questionnaire was sent to 119 orthopaedic and trauma surgery departments in Germany. The acquired form of HO seems to develop after tissue trauma, which induces a local inflammation. A change in tissue conditions, multiple signalling pathways and involvement of several different cell types seem to promote enchondral ossification and finally HO formation. The feed back rate of the survey was 67 %. Eighty-seven percent of all departments currently administer NSAIDs with a mean time span of 3 weeks after surgery for oral prophylaxis. Prophylactic perioperative irradiation is performed in 64 % of trauma/orthopaedic departments if the patient is at risk for HO with a mean dosage of 7 Gy. Basic research detected new pathways and cell signalling mechanisms of HO pathogenesis, which could offer new treatment and prophylaxis options in the near future. So far, there is no uniform strategy for the clinical prophylaxis of HO in THA. Guidelines and new clinical trials need to be developed to further reduce HO rates in THA.

The exact reconstruction of the tibial plateau and articular surface is the main operative aim in the treatment of tibial plateau depression fractures. For selected cases, a novel technique with the use of balloon tibioplasty in combination of bioabsorbable calcium phosphate cement is available. In this study, the first objective was to answer the question whether the clinical outcome parameters after balloon tibioplasty are comparable to open reduction procedures described in the literature. Secondly, we asked whether the cement absorption is safe in relation to adverse effects like osteolysis and measured the absorption ability during the bone conversion process in the proximal tibia bone. Eight patients (mean age 54 years; 4 males and 4 females) received the abovementioned surgical procedure. Mean follow-up period was 27 months. This study evaluated clinical outcome and radiological measured cement absorption within the postoperative course. Cement absorption was measured on X-rays and calculated based on the greatest extend on anterior–posterior and lateral view radiographs just after the operation on the latest available follow-up. WOMAC score showed a mean of 93. Radiologic absorption was 1/5 at a mean of 18 months. No osteolysis reaction was seen surrounding the cement. This far, promising clinical and radiological results have been shown with WOMAC scores comparable to the results of noninjured knees. The indication for this relatively new technique is restricted to isolated depression fractures. It is a useful tool to facilitate the reduction of select depressed tibial fractures. The radiologic absorption effect seems to be quite fast in bone remodeling and safe without any osteolysis or osseous reaction.

Restoration of biomechanics is a major goal in THA. Imageless navigation enables intraoperative control of leg length equalization and offset reconstruction. However, the effect of navigation compared with intraoperative fluoroscopy is unclear.We asked whether intraoperative use of imageless navigation (1) improves the relative accuracy of leg length and global and femoral offset restoration; (2) increases the absolute precision of leg length and global and femoral offset equalization; and (3) reduces outliers in a reconstruction zone of ± 5 mm for leg length and global and femoral offset restoration compared with intraoperative fluoroscopy during minimally invasive (MIS) THA with the patient in a lateral decubitus position.In this prospective study a consecutive series of 125 patients were randomized to either navigation-guided or fluoroscopy-controlled THA using sealed, opaque envelopes. All patients received the same cementless prosthetic components through an anterolateral MIS approach while they were in a lateral decubitus position. Leg length, global or total offset (representing the combination of femoral and acetabular offset), and femoral offset differences were restored using either navigation or fluoroscopy. Postoperatively, residual leg length and global and femoral offset discrepancies were analyzed on magnification-corrected radiographs of the pelvis by an independent and blinded examiner using digital planning software. Accuracy was defined as the relative postoperative difference between the surgically treated and the unaffected contralateral side for leg length and offset, respectively; precision was defined as the absolute postoperative deviation of leg length and global and femoral offset regardless of lengthening or shortening of leg length and offset throughout the THA. All analyses were performed per intention-to-treat.Analyzing the relative accuracy of leg length restoration we found a mean difference of 0.2 mm (95% CI, -1.0 to +1.4 mm; p = 0.729) between fluoroscopy and navigation, 0.2 mm (95 % CI, -0.9 to +1.3 mm; p = 0.740) for global offset and 1.7 mm (95 % CI, +0.4 to +2.9 mm; p = 0.008) for femoral offset. For the absolute precision of leg length and global and femoral offset equalization, there was a mean difference of 1.7 ± 0.3 mm (p0.001) between fluoroscopy and navigation. The biomechanical reconstruction with a residual leg length and global and femoral offset discrepancy less than 5 mm and less than 8 mm, respectively, succeeded in 93% and 98%, respectively, in the navigation group and in 54% and 95%, respectively, in the fluoroscopy group.Intraoperative fluoroscopy and imageless navigation seem equivalent in accuracy and precision to reconstruct leg length and global and femoral offset during MIS THA with the patient in the lateral decubitus position.

Minimally invasive surgery (MIS) is becoming increasingly popular. Supporters claim that the main advantages of MIS total hip replacement (THR) are less pain and a faster rehabilitation and recovery. Critics claim that safety and efficacy of MIS are yet to be determined. We focused on a biomechanical comparison between surgical standard and MIS approaches for THR during the early recovery of patients. A validated, parameterized musculoskeletal model was set to perform a squat of a 50th percentile healthy European male. A bilateral motion was chosen to investigate effects on the contralateral side. Surgical approaches were simulated by excluding the incised muscles from the computations. Resulting hip reaction forces and their symmetry and orientation were analyzed. MIS THR seemed less influential on the symmetry index of hip reaction forces between the operated and nonoperated leg when compared to the standard lateral approach. Hip reaction forces at peak loads of the standard transgluteal approach were 24% higher on the contralateral side when compared to MIS approaches. Our results suggest that MIS THR contributes to a greater symmetry of hip reaction forces in absolute value as well as force-orientation following THR

Successful biomechanical reconstruction is a major goal in total hip arthroplasty (THA). We measured leg length (LL), global (GO) and femoral offset (FO) change on anteroposterior pelvis radiographs and on three-dimensional computed-tomography (3D-CT) with fiducial landmarks after cementless THA on 18 hips of cadaveric specimens. Measurements on radiographs were performed twice by four examiners and showed high interobserver (mean CCC ≥ 0.79) and intraobserver agreements (mean ICC ≥ 0.88). Mean differences between radiographic and 3D-CT measurements were 1.0 (SD 2.0) mm for LL, 0.6 (SD 3.6) mm for GO and 1.4 (SD 5.2) mm for FO. 1% of radiographic LL-, 15% of GO- and 35% of FO measurements were outside a tolerance limit of 5 mm. Radiographs seem acceptable for measuring LL/GO change but fail to reflect FO change in THA.

Persistierende und neu auftretende Beschwerden nach Implantation einer Knietotalendoprothese (K-TEP) sind ein haufiges Problem fur den Orthopaden in Klinik und Praxis. Die Suche nach Ursachen und eine Diagnosefindung gestalten sich aufgrund der Vielzahl moglicher Einflussfaktoren oftmals schwierig. Die schmerzhafte K-TEP fordert Geduld vom orthopadischen Chirurgen, aber auch vom Patienten. Die Indikation zur operativen Revision sollte grundsatzlich mit Bedacht gestellt werden, konservative Therapieverfahren konnen zur betrachtlichen Beschwerdebesserung beitragen. Der im Beitrag vorgestellte, strukturierte Behandlungsalgorithmus hilft beim Einschlagen einer therapeutischen Richtung und falls notwendig bei der Indikationsstellung zur Revisions- oder Wechseloperation. Er bietet die Moglichkeit einer systematischen Eingruppierung nach klinischen, radiologischen und laborchemischen Gesichtspunkten und hilft bei der Entscheidung zur weiteren Verfahrensweise, abgestimmt auf die 4 Differenzialdiagnosen Bewegungseinschrankung, Instabilitat, Lockerung und Infekt. Revisionsoperationen sollten spezialisierten Zentren vorbehalten bleiben und patientenindividuell erfolgen. Eine umfangreiche Kenntnis in der Kniegelenkbiomechanik und Erfahrungen mit der grosen Bandbreite an modularen und achsgekoppelten Revisionssystemen sind fur Revisionsoperateure essenziell.

Die Implantation eines kunstlichen Kniegelenks gehort zu den haufigsten operativen Eingriffen in deutschen Krankenhausern. Navigationsverfahren haben sich dabei in den Operationssalen vieler Kliniken zu einem integralen Bestandteil entwickelt. Orthopadische Chirurgen, die eine moglichst genaue Rekonstruktion der mechanischen Beinachse umsetzen mochten und eine intraoperative Kontrolle der dreidimensionalen Komponentenposition und/oder der kapsular-ligamentaren Situation wunschen, finden in der Navigation ein probates intraoperatives Hilfsmittel. Die unmittelbare intraoperative Kontrollmoglichkeit von knochernen Resektionen und des kapsular-ligamentaren Weichteilbalancings machen die Navigation daruber hinaus zu einem wertvollen Instrument fur das biomechanische Grundverstandnis bei Ausbildungsoperationen fur Weiterbildungsassistenten. Die grosere Prazision bei der Anwendung des Verfahrens spiegelt sich bislang nicht mehrheitlich in einer verbesserten postoperativen Kniefunktion oder einer hoheren Standzeit der Kunstgelenke wider. Neue Entwicklungen in der navigierten Knieendoprothetik stellen die pinfreie Navigation und die Navigationskinematik dar. Bei der pinfreien („pinless“) Navigation wird das konventionell im Oberschenkel- und Schienbeinknochen befestigte Referenzmarkersystem durch ein nichtinvasives Referenzsystem ersetzt. Mithilfe der Navigationskinematik besteht die Moglichkeit, die tibiofemorale sowie patellofemorale Bewegungsdynamik intraoperativ abzubilden. Ziel der nachsten Generation von Navigationssystemen fur die computerassistierte Knieendoprothetik ist eine an der patientenindividuellen Anatomie ausgerichtete Implantatpositionierung mit hohem/stabilem Bewegungsumfang bei optimierter patellarer Fuhrung und Kinematik des Kunstgelenks.