[Promoting young academics in anesthesiology: factors for an attractive internship]. / Nachwuchsförderung in der Anästhesiologie: attraktive Gestaltung der Famulatur.

BACKGROUND: Practical experiences in clinical traineeships can shape the later specialty choice of medical students. KEY QUESTION: The following study aimed to find factors in anesthesiological clinical traineeship that encourage students to specialize in the field. MATERIAL AND METHODS: As part of a nationwide online survey conducted by the working group for education of the German Association for Orthopedics and Trauma Surgery (Deutsche Gesellschaft für Orthopädie und Unfallchirurgie, DGOU), study participants (n = 479) answered questions about their minimum 4­week traineeship in anesthesiology. The information on items was analyzed in six content categories: 1) integration into the team, 2) acquisition of skills, 3) teachers, 4) quality of teaching, 5) structure of teaching and 6) satisfaction with the clinical internship. The respondents were subdivided into 4 groups by answering the question "Could you imagine an elective in anesthesiology during the final year (PJ)" with "Yes, I have made this decision after the clinical traineeship" (JdF, n = 212, 44%), "No I have decided against an elective during the final year after the traineeship" (NdF, n = 56, 12%), "Yes I have decided for an elective in anesthesiology before the internship" (JvF Yes: n = 144, 30%) and "No, I have decided against an elective in anesthesiology before the internship" (NvF: n = 67, 14%). Answers of the participants regarding the six content categories were compared between the four groups. RESULTS: The survey reached all medical faculties in Germany and included participants with an average age of 25.8 years and a balanced gender ratio. There were significant differences between satisfied and dissatisfied students in all four subgroups. Of the 479 respondents, 211 (44%) were already set regarding their decision of choosing anesthesiology as an elective during the final year before the clinical traineeship. Of the respondents 268 (56%) were influenced by the internship, 212 (44%) of them positively. In total, 81% of the trainees rated the internship as "satisfying". Students who were satisfied with the overall internship and who spoke in favor of the PJ elective in anesthesiology differed significantly from the other groups in the categories of team integration, skills acquisition, structure and quality of teaching. The teaching of practical skills and specialist knowledge as well as the integration into diagnostics and treatment planning promoted the recruitment of young people. DISCUSSION: The positively evaluated anesthesiology internship promotes later specialty choice, with quality and structure of the teaching affecting student satisfaction. Trainees who were attracted by anesthesiology gave better overall ratings and acquired more skills during the course of the internship. In order to win aspiring doctors for anesthesiology, the medical team has to integrate trainees well and support the acquisition of practical skills and specialist knowledge. In addition, didactics and practical relevance should be given high priority.

Results after arthroscopic treatment of iliopsoas impingement after total hip arthroplasty.

BACKGROUND: A cause of groin pain after total hip arthroplasty (THA) is mechanical irritation or impingement of the iliopsoas tendon. The incidence is about 4%. If conservative therapy fails, an arthroscopic release of the iliopsoas tendon can be performed. The aim of the study was to assess the mid-term clinical outcome after arthroscopic release. We hypothesize that good results can be achieved by a minimally invasive endoscopic procedure. METHODS: Using our in-house database, all patients who received an endoscopic release of the iliopsoas tendon due to mechanical irritation after THA were identified. Inclusion criteria were mechanical irritation of the iliopsoas tendon after cementless THA with minimal acetabular component prominence. Exclusion criteria were marked prominence of the acetabular component and groin pain after THA for any other reason. In these patients, the modified Harris Hip Score (mHHS), the pain level using the numerical analogue scale and the UCLA Activity Score were measured. The mean follow-up period was 7 ± 3.8 (2.6-11.7) years. RESULTS: 25 patients were identified in whom an arthroscopic release of the iliopsoas tendon had been performed since 2007. The data of 20 patients were available at follow-up. The gender ratio was 1:1, the average age at the time of arthroscopy was 59 ± 27.7 (52-78) years. The average interval between THA and arthroscopy was 6.3 ± 4.0 (1.7-15) years. The mHHS showed a significant improvement from preoperative 31.2 ± 9.8 (17.6-47.3) to 82.0 ± 9.8 (46.2-100) points (p = 0.001). The pain level on the NAS decreased significantly from 8.5 ± 1.2 (7-10) to 2.5 ± 1.8 (0-6) points (p = 0.001). The activity level based on the UCLA Activity Score raised from 4.0 ± 2.7 (0-7) to 6.5 ± 1.8 (3-9) (p = 0.09). CONCLUSION: Mechanical irritation and impingement of the iliopsoas tendon is an important diagnosis to be considered in persistent groin pain after total hip arthroplasty. In failure of non-operative treatment, good clinical results can be achieved with arthroscopic release and the pain level can be significantly reduced. LEVEL OF EVIDENCE: IV.

[Hemitrapeziectomy of the carpometacarpal joint of the thumb]. / Hemiresektionsarthroplastik am Daumensattelgelenk.

BACKGROUND: Hemiresection arthoplasty or partial trapeziectomy of the carpometacarpal joint of the thumb is a surgical option in stages 1-3 according to Eaton-Littler classification. Preservation of the intact scaphotrapeziotrapezoidal (STT) joint and maintenance of the length of the thumb is the advantage of this technique. TECHNIQUE: Technically, partial trapeziectomy is only slightly more complex compared to trapeziectomy with or without suspension. An interposition of autologous or allogeneic material is recommended; suspension arthroplasty is also possible in almost all common variants. Despite these theoretical advantages, this technique has not proven advantageous in practice, neither in terms of function nor in terms of time, compared to other techniques. The great advantage of partial trapeziectomy, however, is the wide range of options for revision surgery in the case of persistent complaints. RESULTS: The risk of proximalization of the thumb due to an inadequate interposition is generally minor and is usually caused by implant sintering. This can easily be compensated for by implanting a larger graft. Persistent instabilities are the most common cause of persistence of symptoms and can usually be remedied by autologous or allogeneic suspension arthroplasty. In addition, the entire range of endoprosthetics is also possible with a previous spare resection of the trapezium and the possibility of a complete trapeziectomy remains in any case. The obvious theoretical advantages of arthroscopic hemitrapeziectomy need to be confirmed in practice in future.

Assessment of acetabular chondral damage and labral pathologies via direct MR arthrography: specialization matters.

AIMS: To compare the diagnostic accuracy of investigators from different specialities (radiologists and orthopaedic surgeons) with varying levels of experience of 1.5 T direct magnetic resonance arthrography (dMRA) against intraoperative findings in patients with femoroacetabular impingement syndrome (FAIS). METHODS: A total of 272 patients were evaluated with dMRA and subsequent hip arthroscopy. The dMRA images were evaluated independently by two non-hip-arthroscopy-trained orthopaedic surgeons, two fellowship-trained musculoskeletal radiologists, and two hip-arthroscopy-trained orthopaedic surgeons. The radiological diagnoses were compared with the intraoperative findings. RESULTS: Hip arthroscopy revealed labral pathologies in 218 (79%) and acetabular chondral lesions in 190 (69%) hips. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy for evaluating the acetabular labral pathologies were 79%, 18%, 79%, 18%, and 66% (non-hip-arthroscopy trained orthopaedic surgeons), 83%, 36%, 83%, 36%, and 74% (fellowship-trained musculoskeletal radiologists), and 88%, 53%, 88%, 54% and 81% (hip-arthroscopy trained orthopaedic surgeons). The sensitivity, specificity, PPV, NPV and accuracy of dMRA for assessing the acetabular chondral damage were 81%, 36%, 71%, 50%, and 66% (non-hip-arthroscopy trained orthopaedic surgeons), 84%, 38%, 75%, 52%, and 70% (fellowship-trained musculoskeletal radiologists), and 91%, 51%, 81%, 73%, and 79% (hip-arthroscopy trained orthopaedic surgeons). The hip-arthroscopy trained orthopaedic surgeons displayed the highest percentage of correctly diagnosed labral pathologies and acetabular chondral lesions, which is significantly higher than the other two investigator groups (p < 0.05). CONCLUSION: The accuracy of dMRA on detecting labral pathologies or acetabular chondral lesions depends on the examiner and its level of experience in hip arthroscopy. The highest values are found for the hip-arthroscopy-trained orthopaedic surgeons. LEVEL OF EVIDENCE: Retrospective cohort study; III.

Defining the Gothic Arch Angle (GAA) as a radiographic diagnostic tool for instability in hip dysplasia.

In recent years, there has been a controversial discussion about whether borderline dysplastic hips should be treated with an arthroscopic procedure or rather with an acetabular reorientation. New research suggests that a classification into stable and unstable hips may be helpful. The aim of the study was to validate (1) the intra- and interobserver reliability of a newly defined radiographic parameter named the Gothic, (2) the association between the GAA and previously existing measurements used to define severity of acetabular dysplasia, and (3) the correlation between radiographic measurements of acetabular dysplasia with MRI findings previously suggestive of hip instability. We defined and validated the GAA in 10 standardized radiographs of asymptomatic hips by two observers and calculated intra- and interobserver coefficients at two individual dates. Subsequently, a consecutive series of 100 patients with dysplastic hips (LCEA < 25°, Toennis grade ≤ 1) were evaluated for signs of instability on anteroposterior (a.p.) pelvic radiographs and direct MR arthrography and were divided in two groups: stable and unstable. In these patients the LCEA, the AI, the FEAR index and the GAA were radiographically evaluated. Correlation analyses and a logistic regression analysis was performed to identify the predictive value of instability for each radiographic parameter. Cutoff probabilities analysis was performed using standard receiver operating characteristic (ROC) curves to rate the predictive efficiency value of the GAA. The GAA showed excellent inter- and intraobserver reliability. A correlation was found between GAA and FEAR index. A logistic regression analysis showed that LCEA, FEAR index and GAA are distinct predictors of instability in hip dysplasia. The GAA showed the largest area under the curve (AUC 0.96), indicating it to be the best predictor of instability with an optimal cutoff value of 90° (sensitivity, 0.95; specificity, 0.93). The GAA is a new available indicator for instability and is thus suggested to be used as a future radiographic parameter for the stability of dysplastic hips. Further studies are needed to understand how this parameter might additionally predict clinical outcome in the treatment of hip dysplasia.Level of evidence: Level III, diagnostic study.

[Risk factors and management strategies for early and late infections following reconstruction with special tumour endoprostheses]. / Risikofaktoren und Managementstrategien des Früh- und Spätinfektes nach Rekonstruktion mit Tumorspezialendoprothesen.

BACKGROUND: Periprosthetic joint infection (PJI) of megaprostheses occur in about 10% of all cases. The criteria for PJI are defined by the "Musculoskleletal Infection Society" (MSIS) and apply to both primary arthroplasty and megaprostheses. MANAGEMENT: The management strategies of PJI in megaprostheses are dependent on the duration of infection and the maturity of the bacterial biofilm. Implant retention with an exchange of the mobile components is only possible in the presence of an immature biofilm. In the presence of a mature biofilm, a one- or two-stage exchange must be performed. A complete exchange of all endoprosthetic components should be performed, if possible, since a partial retention of isolated components results in inferior treatment success rates. RESULTS: The highest success rates are achievable with two-stage exchanges. Multiple risk factors such as skin necrosis, postoperative haematoma, prolonged wound secretion and operative times ≥ 2.5 h are risk factors for the development of PJI in megaprostheses. Knowledge regarding these risk factors allows for an identification of high-risk patients and early management of PJI.

Reconstruction of acetabular defects with porous tantalum shells and augments in revision total hip arthroplasty at ten-year follow-up.

AIMS: The use of trabecular metal (TM) shells supported by augments has provided good mid-term results after revision total hip arthroplasty (THA) in patients with a bony defect of the acetabulum. The aim of this study was to assess the long-term implant survivorship and radiological and clinical outcomes after acetabular revision using this technique. PATIENTS AND METHODS: Between 2006 and 2010, 60 patients (62 hips) underwent acetabular revision using a combination of a TM shell and augment. A total of 51 patients (53 hips) had complete follow-up at a minimum of seven years and were included in the study. Of these patients, 15 were men (29.4%) and 36 were women (70.6%). Their mean age at the time of revision THA was 64.6 years (28 to 85). Three patients (5.2%) had a Paprosky IIA defect, 13 (24.5%) had a type IIB defect, six (11.3%) had a type IIC defect, 22 (41.5%) had a type IIIA defect, and nine (17%) had a type IIIB defect. Five patients (9.4%) also had pelvic discontinuity. RESULTS: The overall survival of the acetabular component at a mean of ten years postoperatively was 92.5%. Three hips (5.6%) required further revision due to aseptic loosening, and one (1.9%) required revision for infection. Three hips with aseptic loosening failed, due to insufficient screw fixation of the shell in two and pelvic discontinuity in one. The mean Harris Hip Score improved significantly from 55 (35 to 68) preoperatively to 81 points (68 to 99) at the latest follow-up (p < 0.001). CONCLUSION: The reconstruction of acetabular defects with TM shells and augments showed excellent long-term results. Supplementary screw fixation of the shell should be performed in every patient. Alternative techniques should be considered to address pelvic disconinuity. Cite this article: Bone Joint J 2019;101-B:311-316.

Cup-cage reconstruction for severe acetabular bone loss and pelvic discontinuity: Mid-term Results of a Consecutive Series of 35 Cases.

AIMS: Severe acetabular bone loss and pelvic discontinuity (PD) present particular challenges in revision total hip arthroplasty. To deal with such complex situations, cup-cage reconstruction has emerged as an option for treating this situation. We aimed to examine our success in using this technique for these anatomical problems. PATIENTS AND METHODS: We undertook a retrospective, single-centre series of 35 hips in 34 patients (seven male, 27 female) treated with a cup-cage construct using a trabecular metal shell in conjunction with a titanium cage, for severe acetabular bone loss between 2011 and 2015. The mean age at the time of surgery was 70 years (42 to 85) and all patients had an acetabular defect graded as Paprosky Type 2C through to 3B, with 24 hips (69%) having PD. The mean follow-up was 47 months (25 to 84). RESULTS: The cumulative five-year survivorship of the implant with revision for any cause was 89% (95% confidence interval (CI) 72 to 96) with eight hips at risk. No revision was required for aseptic loosening; however, one patient with one hip (3%) required removal of the ischial flange of the cage due to sciatic nerve irritation. Two patients (6%; two hips) suffered from hip dislocation, whereas one patient (one hip) required revision surgery with cement fixation of a dual-mobility acetababular component into a well-fixed cup-cage construct. Two patients (6%; two hips) developed periprosthetic infection. One patient was successfully controlled with a two-stage revision surgery, while the other patient underwent excision arthroplasty due to severe medical comorbidities. For the whole series, the Harris Hip Score significantly improved from a mean of 30 (15 to 51) preoperatively to 71 (40 to 89) at the latest follow-up (p < 0.001). CONCLUSION: Our findings suggest that cup-cage reconstruction is a viable option for major segmental bone defects involving the posterior column and PD. It allows adequate restoration of the acetabulum centre with generally good stability and satisfactory postoperative function. Instability and infection remain drawbacks in these challenging revision cases. Cite this article: Bone Joint J 2018;100-B:1442-48.

Evaluation of bone viability in patients after girdlestone arthroplasty: comparison of bone SPECT/CT and MRI.

PURPOSE: To test the diagnostic performance of bone SPECT/CT and MRI for the evaluation of bone viability in patients after girdlestone-arthroplasty with histopathology used as gold standard. MATERIALS AND METHODS: In this cross-sectional study, patients after girdlestone-arthroplasty were imaged with single-photon-emission-computed-tomography/computed-tomography (SPECT/CT) bone-scans using 99mTc-DPD. Additionally, 1.5 T MRI was performed with turbo-inversion-recovery-magnitude (TIRM), contrast-enhanced T1-fat sat (FS) and T1-mapping. All imaging was performed within 24 h prior to revision total-hip-arthroplasty in patients with a girdlestone-arthroplasty. In each patient, four standardized bone-tissue-biopsies (14 patients) were taken intraoperatively at the remaining acetabulum superior/inferior and trochanter major/minor. Histopathological evaluation of bone samples regarding bone viability was used as gold standard. RESULTS: A total of 56 bone-segments were analysed and classified as vital (n = 39) or nonvital (n = 17) by histopathology. Mineral/late-phase SPECT/CT showed a high sensitivity (90%) and specificity (94%) to distinguish viable and nonviable bone tissue. TIRM (sensitivity 87%, specificity 88%) and contrast-enhanced T1-FS (sensitivity 90%, specificity 88%) also achieved a high sensitivity and specificity. T1-mapping achieved the lowest values (sensitivity 82%, specificity 82%). False positive results in SPECT/CT and MRI resulted from small bone fragments close to metal artefacts. CONCLUSIONS: Both bone SPECT/CT and MRI allow a reliable differentiation between viable and nonviable bone tissue in patients after girdlestone arthroplasty. The findings of this study could also be relevant for the evaluation of bone viability in the context of avascular bone necrosis.

[Treatment of acetabular defects with the trabecular metal revision system]. / Defektadaptierte azetabuläre Versorgung mit der Trabecular-Metal-Technologie.

BACKGROUND: The results after acetabular component revision are very heterogeneous, irrespective of the use of established or new components. This could be due to a lack of treatment standards for new revision components. The Trabecular Metal™ (TM) revision system, through its modularity, allows for an individual intraoperative reconstruction of the acetabular defect with a single implant system. It was the aim of this study to investigate the results of acetabular revision with the TMT system taking into consideration the utilized components and the acetabular defect. METHODS: A total of 200 consecutive isolated revisions of the acetabular component from 2010 until 2012 were retrospectively analyzed from our institutional database. Of the 200 cases, 114 revisions were performed with a combination of different TMT components (wedge and cup, cup and cage). Aseptic cup failure and revision for any reason were the defined endpoints of this study. The acetabular defects were graded according to the Paprosky classification. RESULTS: The average patient age was 63.6 ± 14.8 years (range 32-85 years) and the average follow-up was 5.3 ± 0.7 years. The overall revision rate, independent of the utilized components, was 4.4% and the revision rate for aseptic failure of the acetabular component was 2.6%. The revision rate for aseptic loosening for Paprosky type I and II defects was 0% and Paprosky type III and IV defects was 12%. CONCLUSIONS: The modular TMT system shows low revision rates. The modularity of the system allows for a safe and intraoperative adaptation to the individual acetabular defect without the need for extensive preoperative imaging or custom-made implants.

Do post-operative changes of neck-shaft angle and femoral component anteversion have an effect on clinical outcome following uncemented total hip arthroplasty?

The accurate reconstruction of hip anatomy and biomechanics is thought to be important in achieveing good clinical outcomes following total hip arthroplasty (THA). To this end some newer hip designs have introduced further modularity into the design of the femoral component such that neck-shaft angle and anteversion, which can be adjusted intra-operatively. The clinical effect of this increased modularity is unknown. We have investigated the changes in these anatomical parameters following conventional THA with a prosthesis of predetermined neck-shaft angle and assessed the effect of changes in the hip anatomy on clinical outcomes. In total, 44 patients (mean age 65.3 years (standard deviation (SD) 7); 17 male/27 female; mean body mass index 26.9 (kg/m²) (SD 3.1)) underwent a pre- and post-operative three-dimensional CT scanning of the hip. The pre- and post-operative neck-shaft angle, offset, hip centre of rotation, femoral anteversion, and stem alignment were measured. Additionally, a functional assessment and pain score were evaluated before surgery and at one year post-operatively and related to the post-operative anatomical changes. The mean pre-operative neck-shaft angle was significantly increased by 2.8° from 128° (SD 6.2; 119° to 147°) to 131° (SD 2.1; 127° to 136°) (p = 0.009). The mean pre-operative anteversion was 24.9° (SD 8; 7.9 to 39.1) and reduced to 7.4° (SD 7.3; -11.6° to 25.9°) post-operatively (p < 0.001). The post-operative changes had no influence on function and pain. Using a standard uncemented femoral component, high pre- and post-operative variability of femoral anteversion and neck-shaft angles was found with a significant decrease of the post-operative anteversion and slight increase of the neck-shaft angles, but without any impact on clinical outcome.

Tranexamic acid reduces the blood loss and blood transfusion requirements following peri-acetabular osteotomy.

We have investigated the effect of using tranexamic acid (TXA) during peri-acetabular osteotomy (PAO) on peri-operative blood loss and blood transfusion requirements. In addition we analysed whether the use of TXA was associated with an increased risk of venous thromboembolism (VTE) following this procedure. A consecutive series of 96 PAOs, performed by a single surgeon, were reviewed. A total of 48 patients received TXA and 48 did not. The TXA group received a continuous infusion of TXA at a rate of 10 mg/kg/h. The primary outcome measure was the requirement for blood transfusion. Secondary outcomes included total blood loss, the decrease in the level of haemoglobin in the blood, the length of hospital stay, and the complications of this treatment. The mean rate of transfusion was significantly lower in the TXA group (62.5% vs 12.5%, p < 0.001). The mean blood loss was also significantly reduced in the TXA group (1.9 L (standard deviation (SD) 0.9) vs 1.5 L (SD 0.7), p < 0.01). No post-operative episodes of VTE were identified in either group. The use of TXA reduced the blood loss and the rate of transfusion after PAO significantly, without adverse effects such as an increased rate of VTE.

Improved identification of polymicrobial infection in total knee arthroplasty through sonicate fluid cultures.

INTRODUCTION: Periprosthetic joint infection (PJI) is the leading cause for early failure of total knee arthroplasty (TKA). An insufficient diagnosis of the involved bacterial species can be a possible cause for this high failure rate. Sonicate fluid cultures (SFC) have been shown to increase the detection rate of PJI in comparison to the use of conventional microbiological methods. The hypothesis of this study is that sonication will improve not only the detection rate of PJI, but also the detection rate of polymicrobial infection in patients with TKA revision surgery. MATERIALS AND METHODS: 109 patients, undergoing TKA revision surgery, were enrolled in this prospective cohort study and received a synovial aspiration, intraoperative tissue cultures, histological sampling of the periprosthetic membrane (PM), and sonication of the explanted endoprosthesis. A PJI was defined according to the following criteria: presence of intraarticular pus or a sinus tract, positive isolation of the same bacterial species in ≥2 microbiological samples or a PM indicative of infection. RESULTS: 31 patients had a defined PJI according to the above-mentioned criteria. SFC achieved the highest sensitivity (74 %) of all microbiological methods. The PM achieved a sensitivity of 87 %. When the results of the SFC and the PM were combined, it was possible to further increase the sensitivity to 94 %. The utilization of SFC doubled the number of polymicrobial bacterial isolations in our patient collective. There were 12 cases of polymicrobial bacterial isolations, six were detectable through conventional microbiological methods, four were detectable through SFC and two were identifiable as polymicrobial through the isolation of an additional bacterial species in the SFC. CONCLUSIONS: In our study, SFC were the most sensitive microbiological method and were surpassed only by the histology. The use of SFC doubled the detection rate of polymicrobial isolations, which would be missed with conventional microbiological methods alone.

[Diagnosis and therapy of particle disease in total hip arthroplasty]. / Diagnostik und Behandlung von Abrieberkrankungen in der Hüftendoprothetik.

Particle disease is caused by periarticular accumulation of attrition particles and the inflammatory reaction of the body's tissue. This process may result in osteolysis or soft tissue transformation which presents itself symptomless in the beginning and can proceed to aseptic implant loosening, fracture, implant breaking as a result of the inappropriate osseous support and to algetic and destructive soft tissue reactions as well. Attrition particles originate from tribological pairing, and the extent of the attrition or the particle concentration depend on different factors as there are the tribological pairing's material, the head size, the patient's level of activity, and the implant position. Attrition particles can also be found in the range of any modular connection. Particle disease and its resulting morphological alterations of the tribological pairing is one of the most frequent reasons for re-operation in hip endoprosthetics.

Significant muscle damage after multiple revision total hip replacements through the direct lateral approach.

Intact abductors of the hip play a crucial role in preventing limping and are known to be damaged through the direct lateral approach. The extent of trauma to the abductors after revision total hip replacement (THR) is unknown. The aim of this prospective study was to compare the pre- and post-operative status of the gluteus medius muscle after revision THR. We prospectively compared changes in the muscle and limping in 30 patients who were awaiting aseptic revision THR and 15 patients undergoing primary THR. The direct lateral approach as described by Hardinge was used for all patients. MRI scans of the gluteus medius and functional analyses were recorded pre-operatively and six months post-operatively. The overall mean fatty degeneration of the gluteus medius increased from 35.8% (1.1 to 98.8) pre-operatively to 41% (1.5 to 99.8) after multiple revision THRs (p = 0.03). There was a similar pattern after primary THR, but with considerably less muscle damage (p = 0.001), indicating progressive muscle damage. Despite an increased incidence of a positive Trendelenburg sign following revision surgery (p = 0.03) there was no relationship between the cumulative fatty degeneration in the gluteus medius and a positive Trendelenburg sign (p = 0.26). The changes associated with other surgical approaches to the hip warrant investigation.

Improvement in the detection rate of PJI in total hip arthroplasty through multiple sonicate fluid cultures.

The microbiological culture of sonicate fluid (SFC) of explanted endoprosthetic components has increased the rate of bacterial isolation in comparison to conventional microbiological methods. However, this creates the problem of interpreting cases of singular bacterial isolation through SFC, while all other microbiological samples remain negative. The aim of this study was to reference these singular positive SFC against, the histological classification of the periprosthetic membrane (PM), and the utilization of multiple SFC (separate sonication of individual endoprosthetic components). In this prospective study we compared the effect of multiple SFC for detection of periprosthetic joint infection (PJI) in patients with total hip revision surgery. All microbiological results were referenced against PM. Of the 102 cases there were 37 cases of PJI. Single SFC achieved the highest sensitivity of all individual parameters with 89% and a specificity of 72%. When multiple SFC were employed the sensitivity and specificity increased to 100%. There was a concordance of 86% between the PM and SFC. SFC achieved the highest sensitivity and it was possible to further improve the sensitivity and specificity when using multiple cultures. Multiple SFC and PM are beneficial to help reference singular bacterial isolations and achieve the diagnosis of PJI.

Treatment of periprosthetic tibial plateau fractures in unicompartmental knee arthroplasty: plates versus cannulated screws.

INTRODUCTION: Periprosthetic tibial plateau fractures (TPF) are rare but represent a serious complication in unicompartmental knee arthroplasty. The most common treatment for these fractures is osteosynthesis with cannulated screws or plates. The aim of this study was to evaluate two different treatment options for periprosthetic fractures. The hypothesis was that angle-stable plates show significantly higher fracture loads than fixation with cannulated screws. MATERIALS AND METHODS: Twelve matched, paired fresh-frozen tibiae with periprosthetic TPF were used for this study. In Group A, osteosyntheses with cannulated screws were performed, whereas in Group B plates fixated the periprosthetic fracture. DEXA bone density measurement and standard X-rays (AP and lateral) were performed before loading the tibiae under standardised conditions with a maximum load of up to 10.0 kN. After the specimens had been loaded, fracture patterns and fracture loads were analysed and correlated with BMD, BMI, bodyweight (BW), age and size of the tibial implant. RESULTS: In the plate group all tibiae fracture occured with a median load of F (max) = 2.64 (0.45-5.68) kN, whereas in the group with cannulated screws fractures occurred at a mean load of F (max) = 1.50 (0.27-3.51) kN. The difference was statistically significant at p < 0.05. DISCUSSION: Angle-stable plates showed significantly higher fracture loads than fixation with cannulated screws. Cannulated screws show a reduced stability of the tibial plateau. Therefore in periprosthetic TPF, osteosyntheses with angle-stable plates should be recommended instead of cannulated screws.

Ultrasound-based computer navigation: an accurate measurement tool for determining combined anteversion?

INTRODUCTION: The present feasibility study examined the use of an ultrasound-based navigation system (UNS) for reliability of measurement the positions of both the femoral and acetabular components, a prerequisite to adjust the combined anteversion with sufficient accuracy when using a femur-first approach in total hip arthroplasty. METHOD: Using a UNS, five investigators performed five measurements of the posterior femoral condyles and the anterior pelvic planes (APP) of two cadavers with different body mass index. Deviations in stem and acetabular anteversion resulting from varying acquisition of the respective landmarks were determined relative to the reference measures of anteversion determined in the same cadavers from computed tomography (CT) scans. Here, both a freehand and guided ultrasound measurement methods were used to acquire the posterior femoral condyles. Femoral and acetabular anteversion values were added in order to estimate the combined anteversion of the reconstructed hip. RESULTS: Using an UNS, variations in the freehand technique for the acquisition of the posterior femoral condyles resulted in a mean error in the anteversion of the femoral component of -1.5° (SD 3.4°; -10.8° to 7.0°) while the mean error was -0.9° (SD 3.1°; -7.3° to 10.2°) when the UNS provided additional support to standardize the orientation of the UNS probe. In all cases, UNS navigation enabled to achieve combined anteversion values that fell within a clinically acceptable error range of less than ± 12.5° compared to the CT measures. CONCLUSION: Our investigations suggest that the anteversion of stem and cup can be measured with accuracy sufficient enough to utilize the concept of combined anteversion using UNS. Hence, the advantage of utilizing UNS's in a femur-first approach is the ability to intraoperatively compensate for deviations from the targeted anteversion of the stem (which is often difficult to control) by adjusting the acetabular anteversion in the final step of the implantation. In doing so, the placement of the components follows the concept of combined anteversion. Avoiding extreme anteversion values of combined anteversion could be an important step towards reducing post-operative complications following total hip arthroplasty (THA).