High risk of hip dislocation following polyethylene liner exchange in total hip arthroplasty-is cup revision necessary?

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.

[Discrepancy between radiographic and true cup position after total hip arthroplasty : Are we interpreting our radiographic quality indicators correctly? Video article]. / Diskrepanz zwischen radiographischer und tatsächlicher Pfannenstellung bei der Hüft-TEP-Versorgung : Interpretieren wir unsere radiologischen Qualitätsindikatoren richtig? Videobeitrag.

BACKGROUND: After total hip arthroplasty (THA), objective postoperative quality control is done via X­rays by as component position assessment. The cup position is defined by its version and inclination. However, there is a discrepancy between radiographically measured and true (anatomic) cup position, which may lead to misinterpretation. METHODS: To visualize the discrepancy between true and radiographically measured cup position, in this video, a cup holder was used to set the angular cup version and inclination. Hereby, the cup position (anteversion and inclination) can be characterized in its radiographic and anatomic definition in greater detail. The viewer of this video should receive an impression as to when radiographically measured cup angles must be considered with caution. RESULTS: In a simultaneous X­ray and image sequence, this video shows decreased radiographic inclination measurement with increasing anterior rotation of the cup exceeding 20° of anteversion, yet with unchanged true inclination on the cup holder. Isolated consideration of the radiographic angles of anteversion and inclination may cause misinterpretation of true cup position. In pectoral illustration we show that variations in cup version and inclination may remain undetected when considering isolated the radiographic cup parameters. CONCLUSION: True cup position in its anatomical definition can be calculated from the radiographically measured position. For this purpose, both cup parameters (radiographic anteversion and radiographic inclination) have to be taken into account.

Assessment of pelvic tilt in anteroposterior radiographs by means of tilt ratios.

INTRODUCTION: In anteposterior (AP) radiographs, cup position in total hip arthroplasty and acetabular anatomy in hip-preserving surgery are highly influenced by pelvic tilt. The sagittal rotation of the anterior pelvic plane is an important measurement of pelvic tilt during hip surgery. Thus, correct evaluation of cup position and acetabular parameters requires the assessment of pelvic tilt in AP radiographs. METHODS: Changes in pelvic tilt inversely change the height of the lesser pelvis and the obturator foramen in AP radiographs. Tilt ratios were calculated by means of these two parameters in simulated radiographs for ten male and ten female pelvises in defined tilt positions. A tilt formula obtained by exponential regression analysis was evaluated by two blinded investigators by means of 14 simulated AP radiographs of the pelvis with pelvic tilts ranging from + 15° to - 15°. RESULTS: No differences were found between male and female tilt ratios for each 5° step of simulated pelvic tilt. Pelvic tilt and tilt ratios correlated exponentially. Using the tilt formula, the two blinded investigators were able to assess pelvic tilt with high conformity, a mean relative error of + 0.4° (SD ± 4.6°), and a mean absolute error of 3.9° (SD ± 2.3°). Neutral pelvic tilt is indicated by a tilt ratio of 0.5 when the height of the lesser pelvis is twice the height of the obturator foramen. CONCLUSION: The analysis and interpretation of cup position and acetabular parameters may be improved by our method for assessing pelvic tilt in AP radiographs.

[Teaching in orthopaedic and trauma surgery]. / Lehre in Orthopädie und Unfallchirurgie.

The scramble for available places to study medicine in Germany continues. One of the core points within the "Master Plan 2020", which has been recently adopted, is the reform of teaching concepts at German medical faculties. In the future, students of human medicine are to be trained primarily based upon competence-oriented, integrated curricula. The present paper is intended to present modern teaching concepts and methods, as well as current examination formats, which play a special role in student training in orthopaedics and traumatology. Knowledge in the field of medical and evidence-based treatment strategies, clinical examination techniques, diagnostic/therapeutic procedures and hygienic working conditions are especially important. Individual courses with a focus on research-, practice- and competence-orientation are intended to help the students grasp the depth of the subject.

[Total knee arthroplasty in the elderly]. / Kniegelenkersatz des älteren Menschen.

BACKGROUND: The number of total knee arthroplasties in elderly patients is increasing in accordance with the demographic shift in the population. OBJECTIVE: Analysis of the special situation in the elderly, conservative treatment options, perioperative risk factors, preoperative preparation, special intraoperative features and outcome. METHODS: Analysis of currently available scientific data and presentation of own scientific study results. RESULTS: Total knee arthroplasty in elderly patients is related to an increased perioperative risk of complications. A thorough interdisciplinary preparation is required to reduce risk factors. Ligament stability of the knee does not correlate with age. The postoperative outcome after total knee arthroplasty in elderly patients is decisively influenced by the preoperative function and psychosocial parameters. CONCLUSION: Total knee arthroplasty in elderly patients is particularly challenging for orthopedic surgeons and requires close interdisciplinary cooperation.

[Patella navigation in computer-assisted TKA : Intraoperative measurement of patellar kinematics. Video article]. / Patellanavigation bei computerassistierter Knie-TEP-Implantation : Eine Technik zur intraoperativen Messung der Patellakinematik. Videobeitrag.

INTRODUCTION: Patellofemoral maltracking is a relevant problem after total knee arthroplasty (TKA). Patella navigation is a tool that allows real time monitoring of patella tracking. MATERIAL: This video contribution demonstrates the technique of patellofemoral navigation and a possible consequence of intraoperative monitoring. A higher postoperative lateral tilt is addressed with a widening of the lateral retinaculum in a particular manner. CONCLUSION: In selected cases of patellofemoral problems, patella navigation is a helpful tool to evaluate patellofemoral tracking intraoperatively. Modifications of implant position and soft tissue measurements can then prevent postoperative patellofemoral maltracking.

Pathogenesis and prevention strategies of heterotopic ossification in total hip arthroplasty: a narrative literature review and results of a survey in Germany.

INTRODUCTION: 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. MATERIALS AND METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

[Bone defect adjusted strategy in revision arthroplasty of the hip : Wich implant in wich situation? Innovations and approved methods]. / Defektadaptierte Rekonstruktionsstrategien in der Hüftrevisionsendoprothetik : Welches Implantat in welcher Situation? Innovationen und Bewährtes.

BACKGROUND: Revision total hip arthroplasty is of rising importance, with 35,000 procedures a year in Germany. OBJECTIVES: Primary stability of the revision implant, reconstruction of the anatomical hip center, reconstruction of bone stock, and permanent secondary integration are the main priorities. METHODS: Current literature and examples from our own experience are presented. RESULTS AND CONCLUSIONS: Novel developments from basic research and industrial partners extend the possibilities for treating affected patients. For an integrated therapy concept in implant selection criteria, such as situation and structure of the defect, combination with any remaining implants, causes of loosening and failure, implant allergy, and patient-specific parameters should be taken into consideration.

[Minimally invasive treatment of depression fractures of the tibial plateau using balloon repositioning and tibioplasty: video article]. / Die minimal-invasive Versorgung von Tibiakopfimpressionsfrakturen mit Hilfe der Ballonreposition und Tibioplastie : Videobeitrag.

BACKGROUND: The aim of surgical treatment of fractures of the tibial head is an exact reconstruction of the joint plateau. For this purpose the method of balloon tibioplasty is now available in selected cases. This article and the accompanying video material illustrate the minimally invasive technique of tibioplasty using an actual example of patient treatment. METHODS: This technique offers gentle reduction by slow expansion of the balloon. The large balloon surface ensures that more bone can be lifted carefully at once in order to achieve the anatomical position. The positioning of the balloon requires surgical precision. Balloon reduction creates a well-defined bone cavity of known volume and is stabilized using calcium phosphate cement. Possible risks are cement leakage and secondary loss of reduction. RESULTS: Thus far, results are promising, but long-term results are still lacking. Therefore, the indication should be made carefully and differentiated.

[Update on navigation in total knee arthroplasty. Where are we today and what lies in the future?]. / Update Navigation in der Knieendoprothetik. Wo stehen wir heute und was bringt die Zukunft?

BACKGROUND: The implantation of an artificial knee is one of the most common operative interventions in German hospitals. Navigation procedures have developed into an integral component of such interventions in the operating theatres of many clinics. METHODS: For orthopedic surgeons who want to implement an as exact as possible reconstruction of the mechanical leg axis and require intraoperative control of the three dimensional positioning of components and/or the capsular ligament situation, navigation is a well-proven intraoperative tool. The immediate intraoperative control possibility of bone resection and capsular ligament soft tissue balancing means that navigation is a valuable instrument for the biomechanical fundamental understanding in training operations for further education of orthopedic surgeons in training. DEVELOPMENTS: The greater precision obtained by the implementation of the procedure has not yet been conclusively reflected in an improved postoperative knee function or an increased durability of prostheses. New developments in navigated knee prostheses are pinless navigation and navigation kinematics. In pinless navigation the conventional reference marker system fixed in the femur and shin bones is replaced by a non-invasive reference system. With the aid of navigation kinematics it is possible to image the tibiofemoral and patellofemoral movement dynamics, intraoperatively. PERSPECTIVE: The aim of the next generation navigation systems for computer-assisted knee prosthetics is implant positioning aligned to the individual anatomy of patients with high and stable range of movement for optimum patellar guidance and kinematics of the artificial joint.

[Painful total knee arthroplasty. A treatment algorithm]. / Die schmerzhafte Knieprothese. Ein Behandlungsalgorithmus.

BACKGROUND: Persisting and newly occurring complaints after implantation of a total knee endoprosthesis (TKE) are common problems for orthopaedic surgeons in clinics and private practices. The search for the cause and the diagnostics are often difficult due to the many possible influencing factors. Painful TKE requires patience from the orthopaedic surgeon as well as from the patient. THERAPY MODALITIES: The indications for surgical revision should basically be considered with caution and conservative therapeutic procedures can contribute to a considerable improvement in complaints. The treatment algorithm presented in this article helps to adopt a therapeutic direction and if necessary in assessing the indications for revision or replacement surgery. The algorithm offers the possibility of a systematic classification according to clinical, radiological and laboratory testing aspects and assists in the decision for further procedures depending on the four differential diagnoses of limitations in movement, instability, loosening and infection. CONCLUSION: Revision operations should be performed in specialized centers and should be tailored to the individual patient. A comprehensive knowledge of knee joint biomechanics and experience with the large spectrum of modular and axis-linked revision systems are essential for revision surgeons.

Treatment of Klippel-Feil syndrome with symptomatic atlantoaxial instability in a 7-year-old boy : A case report.

Klippel-Feil syndrome (KFS) is a congenital deformity of the cervical spine. Clinical symptoms of KFS are reduced range of motion, short neck and low hairline. In adult KFS patients the deformity can lead to adjacent segmental instability with spinal canal stenosis, radiculopathy and myelopathy. This article reports about the diagnostics and treatment management of juvenile KFS patient with myelopathy due to instability of the C1/C2 segment, subsequent stenosis through the posterior arch of C1 and symptomatic myelopathy. This 7­year-old boy could be successfully treated with C1 decompression and computer tomography (CT) guided C1/C2 stabilization with pedicle screws under intraoperative neuromonitoring.

Osteogenic and angiogenic potential of molybdenum-containing mesoporous bioactive glass nanoparticles: An ionic approach to bone tissue engineering.

Biomaterials intended for application in bone tissue engineering (BTE) ideally stimulate osteogenesis and angiogenesis simultaneously, as both mechanisms are of critical importance for successful bone regeneration. Mesoporous bioactive glass nanoparticles (MBGNs) can be tailored towards specific biological needs, for example by addition of ions like Molybdenum (Mo). While Mo has been shown to enhance osteogenic differentiation of human bone marrow-derived mesenchymal stromal cells (BMSCs) as well as their ability to form and mature a primitive osseous extracellular matrix (ECM), there are contradictory findings regarding its impact on angiogenesis. In this study, the effects of Mo-MBGNs (mol%: 70 SiO2, 25 CaO, 5 MoO3) on viability, proliferation, osteogenic differentiation, ECM formation and angiogenic response of BMSCs were compared to undoped MBGNs (in mol%: 70 SiO2, 30 CaO) and a control group of BMSCs. Furthermore, a human umbilical vein endothelial cells tube formation assay and a chorioallantoic membrane-assay using fertilized chicken eggs were used to analyze angiogenic properties. Mo-MBGNs were cytocompatible and promoted the proliferation of BMSCs. Furthermore, Mo-MBGNs showed promising osteogenic properties as they enhanced osteogenic differentiation, ECM formation and maturation as well as the gene expression and protein production of relevant osteogenic factors in BMSCs. However, despite the promising outcome on osteogenic properties, the addition of Mo to MBGNs resulted in anti-angiogenic effects. Due to the high relevance of vascularization in-vivo, the anti-angiogenic properties of Mo-MBGNs might hamper their osteogenic properties and therefore might restrict their performance in BTE applications. These limitations can be overcome by the addition of ions with distinct pro-angiogenic properties to the Mo-MBGNs-composition. Due to their promising osteogenic properties, Mo-MBGNs constitute a suitable basis for further research in the field of ionic (growth factor free) BTE.

Boric acid and Molybdenum trioxide synergistically stimulate osteogenic differentiation of human bone marrow-derived mesenchymal stromal cells.

INTRODUCTION: Metals and their metal ions have been shown to exhibit certain biological functions that make them attractive for use in biomaterials, for example in bone tissue engineering (BTE) applications. Recent data shows that Molybdenum (Mo) is a potent inducer of osteogenic differentiation in human bone marrow-derived mesenchymal stromal cells (BMSCs). On the other hand, while boron (B) has been shown to enhance vascularization in BTE applications, its impact on osteogenic differentiation is volatile: while improved osteogenic differentiation has been described, other data show that B might slow down osteogenic differentiation or reduce the calcification of the extracellular matrix (ECM) when applied in higher doses. Still, the combination of pro-osteogenic Mo and pro-angiogenic B is certainly attractive in the context of biomaterials intended for the use in BTE. METHODS: Therefore, the combined effect of molybdenum trioxide and boric acid at different ratios was investigated in this study to evaluate the effects on the viability, proliferation, osteogenic differentiation, ECM production and maturation of BMSCs. RESULTS: Mo ions proved to be stronger osteoinductive compared to B, in fact, while some osteogenic differentiation markers were downregulated in the presence of B, the presence of Mo provided compensation. The combined application of B and Mo indicated a combination of individual effects, partially even enhancing the expected combined performance of the single stimulations. CONCLUSIONS: The combination of B and Mo might be beneficial for BTE applications since the limited osteogenic properties of B can be compensated by Mo. Furthermore, since B is known to be pro-angiogenic, the combination of both substances may synergistically lead to improved vascularization and bone regeneration. Future studies should assess the angiogenic performance of this combination in greater detail.

Biological effects of a zinc-substituted borosilicate bioactive glass on human bone marrow derived stromal cells in vitro and in a critical-size femoral defect model in rats in vivo.

The borosilicate 0106-B1-bioactive glass (BG) composition (in wt%: 37.5 SiO2, 22.6 CaO, 5.9 Na2O, 4.0P2O5, 12.0 K2O, 5.5 MgO, 12.5 B2O3) has shown favorable processing characteristics and bone regeneration ability. This study investigated the addition of zinc (Zn) to 0106-B1-BG as an approach to improve this BG's biological properties. Different proportions of ZnO were substituted for CaO in 0106-B1-BG, resulting in three new BG-compositions: 1-Zn-BG, 2-Zn-BG, 3-Zn-BG (in wt%: 37.5 SiO2, 21.6/20.1/17.6 CaO, 4.0 P2O5, 5.9 Na2O, 12.0 K2O, 5.5 MgO, 12.5 B2O3 and 1.0/2.5/5.0 ZnO). Effects of the BG compositions on cytocompatibility, osteogenic differentiation, extracellular matrix deposition, and angiogenic response of human bone marrow-derived mesenchymal stromal cells (BMSCs) were evaluated in vitro. Angiogenic effects were assessed using a tube formation assay containing human umbilical vein endothelial cells. The in vivo osteogenic and angiogenic potentials of 3-Zn-BG were investigated in comparison to the Zn-free 0106-B1-BG in a rodent critical-size femoral defect model. The osteogenic differentiation of BMSCs improved in the presence of Zn. 3-Zn-BG showed enhanced angiogenic potential, as confirmed by the tube formation assay. While Zn-doped BGs showed clearly superior biological properties in vitro, 3-Zn-BG and 0106-B1-BG equally promoted the formation of new bone in vivo; however, 3-Zn-BG reduced osteoclastic cells and vascular structures in vivo. The acquired data suggests that the differences regarding the in vivo and in vitro results may be due to modulation of inflammatory responses by Zn, as described in the literature. The inflammatory effect should be investigated further to promote clinical applications of Zn-doped BGs.

[What medical students want - evaluation of medical recruitment ads by future physicians]. / Was Medizinstudierende wollen - Einschätzung ärztlicher Stellenanzeigen durch angehende Ärztinnen und Ärzte der Humanmedizin.

OBJECTIVE: Three-quarters of all hospitals in Germany are now struggling to fill open positions for doctors. The medical job ad is a vital tool for human resources marketing and an important image factor. The present study examines the importance of information and offers in medical recruitment ads on application decisions by medical students. METHOD: A total of 184 future physicians from clinical semesters participated voluntarily in an anonymous cross-sectional survey. Using a standardised questionnaire, the importance of 49 -individual items extracted from medical recruitment ads were rated with the help of a 4-point Likert Scale. Finally, the study participants prioritised their reasons for an application as a physician. RESULTS: Primary influence on the application decision on medical recruitment ads by medical students had offers/information in relation to education and training aspects and work-life balance. Payment rates for physicians and work load played an important role for the application motivation. Additional earnings for, e. g., emergency calls, providing of medical expertise and assistance with housing, relocation and reimbursement of interview expenses were less crucial. In prioritising key reasons for selecting a prospective employer "regular working hours," an "individual training concept" and an "attractive work-life balance" scored the highest priority. The "opportunity for scientific work" was assigned only a small significance. CONCLUSION: High importance for the application decision by future physicians on medical recruitment ads is placed on jobs with an opportunity for personal development and aspects that contribute to work-life balance.

[Treatment of unicompartmental osteoarthritis of the knee]. / Therapie der unikompartimentellen Gonarthrose.

Osteoarthritis of the knee is one of the most important degenerative joint diseases in the clinical routine. The treatment of knee osteoarthritis is not only based on the stage, symptoms and duration of the joint disease, but also depends on the existing arthrosis pattern. In the case of unicompartmental arthrosis, damage typical for osteoarthritis is limited to just one joint compartment. Both the conservative and the surgical treatment of unicompartmental osteoarthritis of the knee have to respect the individual characteristics of the respective forms of osteoarthritis. In the context of this manuscript, the genesis, the diagnostics and the guideline-based stage-adapted conservative and operative treatment of unicompartmental osteoarthritis of the knee are addressed.

[Radiological findings, evaluation and treatment of patellofemoral pain after total knee arthroplasty]. / Radiologische Diagnostik, Beurteilung und Behandlung des patellofemoralen Schmerzes nach primärer Knieendoprothetik.

Total knee arthroplasty (TKA) is one of the most successful operative procedures over the last decades in orthopedic surgery; however, some patients suffer from pain, limited range of motion, instability, infections or other complications postoperatively. Patellofemoral pain (PFP) in particular is a common problem after TKA and often necessitates revision surgery. Mainly increasing and localized contact pressure and patella maltracking are held responsible for PFP but the reasons vary. Diagnostics and therapy of PFP is not easy to manage and should be treated following a clinical pathway. The authors suggest that patients with PFP should be categorized after basic diagnostic measures according to the suspected diagnosis: (1) tendinosis, (2) mechanical reasons, (3) intra-articular non-mechanical reasons and (4) neurogenic/psychiatric reasons. Efficient application of special diagnostic measures and further therapy is facilitated by this classification.