Fixation of intraoperative proximal femoral fractures during THA using two versus three cerclage wires - a biomechanical study.

BACKGROUND: Intraoperative proximal femoral fractures (IPFF) are relevant complications during total hip arthroplasty. Fixation using cerclage wires (CW) represents a minimally-invasive technique to address these fractures through the same surgical approach. The goal of treatment is to mobilise the patient as early as possible, which requires high primary stability. This study aimed to compare different cerclage wire configurations fixing IPFF with regard to biomechanical primary stability. METHODS: Standardised IPFF (type II, Modified Mallory Classification) were created in human fresh frozen femora and were fixed either by two or three CW (1.6 mm, stainless steel). All cadaveric specimens (n = 42) were randomised to different groups (quasi-static, dynamic) or subgroups (2 CW, 3 CW) stratified by bone mineral density determined by Dual Energy X-ray Absorptiometry. Using a biomechanical testing setup, quasi-static and dynamic cyclic failure tests were carried out. Cyclic loading started from 200 N to 500 N at 1 Hz with increasing peak load by 250 N every 100 cycles until failure occurred or maximum load (5250 N) reached. The change of fracture gap size was optically captured. RESULTS: No significant differences in failure load after quasi-static (p = 0.701) or dynamic cyclic loading (p = 0.132) were found between the experimental groups. In the quasi-static load testing, all constructs resisted 250% of the body weight (BW) of their corresponding body donor. In the dynamic cyclic load testing, all but one construct (treated by 3 CW) resisted 250% BW. CONCLUSIONS: Based on this in vitro data, both two and three CW provided sufficient primary stability according to the predefined minimum failure load (250% BW) to resist. The authors recommend the treatment using two CW because it reduces the risk of vascular injury and shortens procedure time.

Simultaneous 18F-FDG-PET/MRI for the detection of periprosthetic joint infections after knee or hip arthroplasty: a prospective feasibility study.

PURPOSE: This study investigated the diagnostic value of simultaneous 18F-fluordeoxyglucose positron emission tomography/magnetic resonance imaging (PET/MRI) in suspected periprosthetic joint infection (PJI) of the hip and knee. METHODS: Sixteen prostheses from 13 patients with suspected PJI were prospectively examined using PET/MRI. Image datasets were evaluated in consensus by a radiologist and a nuclear physician for the overall diagnosis of 'PJI' (yes/no) and its anatomical involvement, such as the periprosthetic bone margin, bone marrow, and soft tissue. The imaging results were compared with the reference standard obtained from surgical or biopsy specimens and subjected to statistical analysis. RESULTS: Using the reference standard, ten out of the 13 prostheses (ten hips, threes knees) were diagnosed with PJI. Using PET/MRI, every patient with PJI was correctly diagnosed (sensitivity, 100%; specificity, 100%). Considering the anatomical regions, the sensitivity and specificity were 57% and 50% in the periprosthetic bone margin, 75% and 33% in the bone marrow, and 100% and 100% in the soft tissue. CONCLUSION: PET/MRI can be reliably used for the diagnosis of PJI. However, assessment of the periprosthetic bone remains difficult due to the presence of artefacts. Thus, currently, this modality is unlikely to be recommended in clinical practice.

Metaphyseal sleeves in arthroplasty of the knee : A suitable tool in management of major metaphyseal bone loss.

BACKGROUND: This study examined the clinical outcome following revision arthroplasty of the knee joint and severe arthrosis with metaphyseal bone defects and instability using metaphyseal sleeves. We analyzed the results based on established scores and recorded the complications occurring on revision arthroplasty. MATERIAL AND METHODS: Patients with revision arthroplasty of the knee and metaphyseal bone defects grade III according to the Anderson Orthopedic Research Institute (AORI) classification were included (16 patients, 9 females and 7 males). In all cases, surgery was performed using an endoprosthesis COMPLETE™ revision knee system with metaphyseal sleeves. RESULTS: All patients had a significant reduction in pain level after revision surgery. The median HSS score in the cohort with primary arthroplasty was 84 and in the cohort with revision arthroplasty 73 and the KSS was 83 and 55, respectively. According to the HSS an excellent result was achieved by 50% of the patients in the primary arthroplasty group and 25% in the revision group. Only three patients were considered to have an insufficient result. Postoperative pain was significantly reduced in both groups. The median ROM was 112° flexion in the primary arthroplasty group and 95° in the revision group. An extension deficit was observed in three patients and four patients showed prolonged wound healing postoperatively (25%), which was treated conservatively and did not lead to septic changes. CONCLUSION: The use of metaphyseal sleeves in patients with bone defects is a suitable instrument with no negative impact on the outcome both in primary and revision arthroplasty. Further studies with larger study groups and analysis of long-term results after use of such endoprosthetic components should be conducted.

Significance of nutritional status in the development of periprosthetic infections : A retrospective analysis of 194 patients.

BACKGROUND: Malnutrition caused by protein and vitamin deficiencies is a significant negative prognostic factor in surgical wound healing disorders and infections. Particularly in elective surgery, preoperative compensation of deficiencies is advisable to avoid negative postoperative consequences. This study examined the nutritional and protein balance of patients with periprosthetic hip and knee joint infections. MATERIAL AND METHODS: Patients with periprosthetic hip or knee joint infections constituted the study group (SG). Control group I (CG I) included patients with primary implants and CG II included patients who required revision surgery because of aseptic loosening. Relevant nutritional and protein parameters were determined via analysis of peripheral venous blood samples. In addition, a questionnaire was used to evaluate the nutritional and eating patterns of all patients. The nutritional risk screening (NRS) 2002 score and body mass index (BMI) were also calculated for all participants. RESULTS: Differences were found in the albumin level (SG: 36.23 ± 7.34, CG I: 44.37 ± 3.32, p < 0.001, CG II: 44.06 ± 4.24, p < 0.001) and total protein in serum (SG: 65.42 ± 8.66, CG I: 70.80 ± 5.33, p = 0.004, CG II: 71.22 ± 5.21, p = 0.004). The number of patients with lowered albumin levels (SG 19/61, CG I 1/78, CG II 2/55) and total protein in serum (SG: 12/61, CG I 5/78, CG II 2/55) also showed considerable variation. The number of patients with a NRS 2002 score ≥3 differed significantly between SG and both CGs (SG: 5/61, CG I 1/78, CG II 0/55); however, these differences could not be confirmed using BMI. CONCLUSION: As expected, lowered albumin and total protein levels were observed in PJI due to the acute phase reaction. The NRS can be performed to exclude nutritional deficiency, which cannot be excluded based on BMI. In cases of periprosthetic joint infection it is reasonable to compensate the nutritional deficiency with dietary supplements.

Knee arthrodesis as last resort for persistent knee joint infections : Comparison of extramedullary and intramedullary treatment.

BACKGROUND: Knee joint arthrodesis is an established treatment for periprosthetic infections (PPI) providing stability and pain relief. In this study the outcome after arthrodesis of the knee joint for persistent infections was compared and evaluated depending on the surgical procedure (intramedullary vs. extramedullary). MATERIAL AND METHODS: In a retrospective case analysis, all patients who underwent knee joint arthrodesis between 1 January 2010 and 31 December 2016 were identified and divided into two groups: IMA and EMA. All patients were examined clinically and radiologically and the patient files were evaluated. In addition, the FIM score, the LEFS, the WHOQOL-BREF and NRS were evaluated. RESULTS: The median LEFS score for the IMA group was 26 points and in the EMA group 2 points (p = 0.03). The IMA patients showed a median pain scale at rest of 0 and during exercise of 2. The EMA group recorded a pain scale of 3 at rest and 5 during exercise (p = 0.28 at rest; p = 0.43 during exercise). In the IMA group the median postsurgical leg length difference was -2.0 cm and -2.5 cm in the EMA group (p = 0.31). At the end of the follow-up examinations, the FIM score of patients in the IMA group was 74.5 points and 22 points in the EMA group (p = 0.07). CONCLUSION: The study showed that no arthrodesis procedure is obviously superior with respect to the postoperative outcome. The IMA combines advantages especially in the early phase after surgery in terms of function as well as patient comfort and is therefore currently the procedure of choice. The attending physician should be familiar with the advantages and disadvantages of the various procedures in order to be able to make an individual decision and thus maximize the chance of treatment success.

Podcasts as a teaching tool in orthopaedic surgery : Is it beneficial or more an exemption card from attending lectures?

OBJECTIVE: The aim of this study was to evaluate the influence of the introduction of online podcasts as part of the main lecture series in orthopaedics on the number of lecture attendees, the examination results and the assessment of teaching by the students. Additionally, we evaluated the use of other media for examination preparation. METHODOLOGY: At the beginning and end of the lecture series questionnaires were handed out to the students to evaluate their attitudes towards attending lectures, the use of video podcasts and examination preparation. In addition, the number of lecture attendees and podcast usage during the semester were counted and the statements of the students in the evaluation assessments of orthopaedic teaching were evaluated. The examination results were correlated in a statistical analysis with the learning materials provided by the students for examination preparation. RESULTS: At the end of the lecture series, 284 students stated that they used the lecture podcast about twice as often as attending lectures; however, for the majority of the students the provision of a video podcast was no reason not to attend the lecture. For example, 37.2% stated that they never and 26.8% stated that they rarely had not attended the lecture by providing the podcasts. Of the students 91-95% considered the availability of lecture podcasts to be a rather meaningful or very meaningful supplement to the lecture visit. Students increasingly used digital media to prepare for examinations instead of using traditional analogue methods. None of the learning methods or materials examined showed a statistically significant advantage in examination results. CONCLUSION: Students in the age of digitalization use a variety of learning materials and are no longer bound to classical analog teaching methods. The use of online podcasts had no negative impact on examination performance. Most students perceived lecture podcasts as a useful supplement to lecture attendance. The students praised the expansion of the teaching curriculum to include additional digital offers with positive comments in the evaluations, but without achieving an improvement in these student evaluations.

Surgical workflow simulation for the design and assessment of operating room setups in orthopedic surgery.

BACKGROUND: The design and internal layout of modern operating rooms (OR) are influencing the surgical team's collaboration and communication, ergonomics, as well as intraoperative hygiene substantially. Yet, there is no objective method for the assessment and design of operating room setups for different surgical disciplines and intervention types available. The aim of this work is to establish an improved OR setup for common procedures in arthroplasty. METHODS: With the help of computer simulation, a method for the design and assessment of enhanced OR setups was developed. New OR setups were designed, analyzed in a computer simulation environment and evaluated in the actual intraoperative setting. Thereby, a 3D graphical simulation representation enabled the strong involvement of clinical stakeholders in all phases of the design and decision-making process of the new setup alternatives. RESULTS: The implementation of improved OR setups reduces the instrument handover time between the surgeon and the scrub nurse, the travel paths of the OR team as well as shortens the procedure duration. Additionally, the ergonomics of the OR staff were improved. CONCLUSION: The developed simulation method was evaluated in the actual intraoperative setting and proved its benefit for the design and optimization of OR setups for different surgical intervention types. As a clinical result, enhanced setups for total knee arthroplasty and total hip arthroplasty surgeries were established in daily clinical routine and the OR efficiency was improved.

Acetabular defect classification and management : Revision arthroplasty of the acetabular cup based on 3-point fixation.

BACKGROUND: The purpose of this study was to provide a practicable and contemporary classification system that is reliable and pragmatic with respect to perioperative evaluation, planning, scientific comparison and analysis. MATERIAL AND METHODS: This was a retrospective study of 160 patients who underwent acetabular revision surgery after THR due to loosening of the acetabular cup. The assessment of the acetabular defect was based on intraoperative description of the bony configuration of the acetabulum as well as on standardized preoperative planning images (pelvic overview and axial view of the hip joint). Preoperative computed tomography (CT) was carried out in individual cases. RESULTS: Acetabular bone defects were classified into 4 types based on whether or not a 3-point fixation of the acetabular cup within the boundaries of the acetabular cavity was possible. Minor segmental defects or cup loosening without bone loss can be treated with standard hemispherical acetabular components. Bone loss can be filled with bone grafts and/or treated by the appropriate acetabular component in order to ensure stable anchorage. When conventional revision cups are no longer suitable a custom made partial pelvic replacement can be used. CONCLUSION: The proposed classification mainly relies on intraoperative findings which were confirmed by preoperative imaging in 154 cases out of 160 (96.25%); however, meticulous preoperative planning based on X­ray radiographs must be carried out. In addition, a CT scan must be performed whenever type III or type IV defects are anticipated. Compared to the existing classification systems, we can state that our classification system is practicable and pragmatic and simplifies the assessment of bone defects.

Erratum to: Management of pelvic discontinuity in revision hip arthroplasty using a cementless acetabular cup with an iliac stem in combination with a cranial strap.

Erratum to: Orthopäde 2018 https://doi.org/10.1007/s00132-018-03675-5 Dear Reader,in the original online version of the article "Management of pelvic discontinuity in revision hip arthroplasty using a cementless acetabular cup with an iliac stem in combination with a cranial strap" in the section ….

Management of pelvic discontinuity in revision arthroplasty : Cementless acetabular cup with iliac stem and cranial strap.

BACKGROUND: Pelvic discontinuity causes severe destruction of the acetabular bony walls and is particularly difficult to manage. This article reports the short-term results and complications encountered in the management of loosening of the acetabular cup with pelvic discontinuity using an acetabular cup with an intramedullary iliac stem combined with an extramedullary iliac plate. MATERIAL AND METHODS: As part of this monocentric retrospective case analysis all patients who underwent acetabular revision surgery after THR due to loosening of the acetabular cup with pelvic discontinuity in this clinic from January 2016 to June 2017 were identified (n = 16). All patients underwent routine clinical and radiological follow-up. In addition, the Harris hip score (HHS) and the Western Ontario and McMaster Universities osteoarthritis index (WOMAC) were evaluated as part of a 1-year follow-up. RESULTS: All patients were treated with an acetabular revision cup of appropriate size with intramedullary iliac stem combined with an anatomical extramedullary iliac plate. On clinical follow-up at 1 year (median follow-up time 14.5 ± 3.3 months), the average HHS was 69.3 ± 14.1 and the average WOMAC was 79.3 ± 11.7. Complications were registered in 7 out of the 16 patients whereby 1 showed aseptic loosening of the revision cup, dislocations were reported in 4 cases and infections in 2 cases. In the case of the two patients with infections a Girdlestone resection arthroplasty had to be performed. CONCLUSION: The overall complications and postoperative outcome in revision surgery after THR reported in the literature were compared to the results of this study. Compared to the results of salvage procedures using large or bipolar heads and Girdlestone resection arthroplasty, satisfactory results were obtained using the acetabular cup with an intramedullary iliac stem combined with an extramedullary iliac plate.

Femoral neck fractures in old age treated with hemiarthroplasty : Effects of preoperative waiting time and timing of surgery on the risk of periprosthetic infections.

BACKGROUND: Hemiarthroplasty is an established treatment for femoral neck fractures (FNF) in old age; however, approximately 20-30% of patients die within 1 year after surgery. Periprosthetic joint infections (PJI) are one of the severest complications and associated with a high mortality rate. In this retrospective study of aged patients with FNF treated with hemiarthroplasty, the incidence of PJI was evaluated with respect to the influence of the delay to and timing of surgical treatment. PATIENTS AND METHODS: The data of patients suffering from FNF and admitted to this hospital between January 2012 and December 2014 were evaluated. Demographic data, timing of surgery, intraoperative complications, PJI and other general complications, hospitalization time and mortality were recorded. RESULTS: In this study 178 patients were included in the follow-up (114 women and 64 men). The median age of the patients was 83 years (range 55-105 years). The rate of PJI was 3.9% (7/178) and mortality was 5.6% (10/178). Patients with PJI after hemiarthroplasty had a significantly longer hospital stay (17 vs. 10 days, p < 0.001) and a higher mortality (28% vs. 4.7%). No significant differences were found between the groups with respect to the time from admission to surgery. CONCLUSION: The occurrence of PJI after hip joint fractures treated with hemiarthroplasty in aged patients is associated with a significant increase in mortality. Risk factors include a longer surgery time, diabetes, intraoperative complications, postoperative bleeding and wound healing disorders. Surgical treatment within the first 24 h should be aimed for but not at the expense of adequate patient preparation or neglecting the patient's individual risk factors.

The impact of capsular repair on the risk for dislocation after revision total hip arthroplasty - a retrospective cohort-study of 259 cases.

BACKGROUND: Dislocation following total hip arthroplasty has to date not been resolved satisfactorily. Previous work has shown that using a less-invasive adaption of Bauer's lateral transgluteal approach with capsular repair significantly reduces dislocation rates in primary total hip arthroplasty. The aim of this retrospective cohort study was to assess whether this approach also helps to reduce the dislocation rate in revision total hip arthroplasty. METHODS: We analyzed revision total hip arthroplasty cases performed between 10/2005 and 12/2013 in our department, classifying capsular repair cases as study group and capsular resection cases as control group. The WOMAC score, the dislocations and the revisions were observed. RESULTS: A total of 259 cases were included, 100 in the study group and 159 in the control group. In the 12-month follow-up, dislocation rates were significantly lower in the study group (3%, n = 3) compared to the control group (21.4%, n = 34; p = 0.001). Overall follow-up periods were 49 and 79 months, revision frequencies were 10 and 29%, pain improvements were 5.5 compared to 4.4 and the WOMAC global scores averaged 2.0 ± 2.1 and 2.9 ± 2.6 for the study group and the control group, respectively. CONCLUSION: The modified, less-invasive, lateral transgluteal approach with capsular repair was accompanied by an 86% reduction in dislocation rates when compared to the conventional technique with capsular resection via the anterolateral Watson-Jones-approach. Capsular repair is possible in about 60% of the revision total hip arthroplasty cases, may be considered as beneficial to avoid dislocation and can therefore be recommended.

Treatment of genu valgum in children by means of temporary hemiepiphysiodesis using eight-plates: short-term findings.

BACKGROUND: Idiopathic genu valgum is a frequently diagnosed growth disorder in adolescence. Whenever the possibilities of conservative therapy have been exhausted, leg straightening by means of hemiepiphysiodesis has become the standard form of treatment. Because of their flexible screw-plate connection, eight-Plates have been reported in the literature to lead to lower complications regarding implant loosening and fracture compared to other implants. The aim of this retrospective survey was to analyse our own patient population who were treated for genu valgum by means of temporary hemiepiphysiodesis near the knee using eight-Plates to modulate growth. METHODS: Between July 2007 and July 2015, 198 eight-Plates were implanted near the knee in 132 children suffering from genu valgum to modulate growth. Depending on the deformity analysis, an eight-Plate was implanted on the distal medial femur and/or the proximal medial tibia. By December 2015, they had been removed from 105 patients. The etiology of genu valgum was mainly idiopathic or associated withobesity. Evaluation was carried out clinically and radiologically (whole-leg X-ray in standing) including determination of the joint angles. RESULTS: The median follow-up period was about 46 months (12-102 months). The median age at implantation was 12.7 +/-6.76 years. Of the 105 patients, 45.7% (n = 48) were girls. The eight-Plates remained in place for a median period of 13 +/-1.76 months. Irrespective of the location of hemiepiphysiodesis, the intermalleolar distance was corrected to a median of 0 +/-2.1 cm while the anatomical femorotibial angle was corrected by on average 9 +/-2.7 °Mechanical lateral distal femoral angle changed an average 7 +/- 7.72 degrees. Medial proximal tibial angle changed an average 4 +/- 6.02 degrees. Complications necessitating surgery occurred in 2.8% of cases (1 wound infection, 3 corrective osteotomies following overcorrection). CONCLUSION: Temporary hemiepiphysiodesis using eight-Plates is a gentle, simple and effective procedure used to treat genu valgum by modulating growth. Slight overcorrection is desirable due to the rebound phenomenon, especially in young patients with high growth potential and risk groups such as obese children. In adolescents with only low growth potential (older than 14 years), owing to the low correction potential, the indication should be strictly reviewed and the possible failure of therapy should be discussed with the patient. No differences were observed regarding the location of the implanted eight-Plates (femoral or tibial).

A new classification of TKA periprosthetic femur fractures considering the implant type.

BACKGROUND: The treatment aims of periprosthetic fractures (PPF) of the distal femur are a gentle stabilization, an early load-bearing capacity and a rapid postoperative mobilization of the affected patients. For the therapy planning of PPF a standardized classification is necessary which leads to a clear and safe therapy recommendation. Despite different established classifications, there is none that includes the types of prosthesis used in the assessment. For this purpose, the objective of this work is to create a new more extensive fracture and implant-related classification of periprosthetic fractures of the distal femur based on available classifications which allows distinct therapeutic recommendations. METHODS: In a retrospective analysis all patients who were treated in the University Hospital Leipzig from 2010 to 2016 due to a distal femur fracture with total knee arthroplasty (TKA) were established. To create an implant-associated classification the cases were discussed in a panel of experienced orthopaedists and well-practiced traumatologists with a great knowledge in the field of endoprosthetics and fracture care. In this context, two experienced surgeons classified 55 consecutive fractures according to Su et al., Lewis and Rorabeck and by the new created classification. In this regard, the interobserver reliability was determined for two independent raters in terms of Cohen Kappa. RESULTS: On the basis of the most widely recognized classifications of Su et al. as well as Lewis and Rorabeck, we established an implant-dependent classification for PPF of the distal femur. In accordance with the two stated classifications four fracture types were created and defined. Moreover, the four most frequent prosthesis types were integrated. Finally, a new classification with 16 subtypes was generated based on four types of fracture and four types of prosthesis. Considering all cases the presented implant-associated classification (κ = 0.74) showed a considerably higher interobserver reliability compared to the other classifications of Su et al. (κ = 0.39) as well as Lewis and Rorabeck (κ = 0.31). Excluding the cases which were only assessable by the new classification, it still shows a higher interobserver reliability (κ = 0.70) than the other ones (κ = 0.63 or κ = 0.45). CONCLUSIONS: The new classification system for PPF of the distal femur following TKA considers fracture location and implant type. It is easy to use, shows agood interobserver reliability and allows conclusions to be drawn on treatment recommendations. Moreover, further studies on the evaluation of the classification are necessary and planned.

Silver-coated modular Megaendoprostheses in salvage revision arthroplasty after periimplant infection with extensive bone loss - a pilot study of 34 patients.

BACKGROUND: Hip and knee replacements in patients with bone defects after infection correlates with high rates of reinfection. In this vulnerable patient population, the prevention of reinfection is to be considered superordinate to the functionality and defect bridging. The use of silver coating of aseptic implants as an infection prophylaxis is already proven; however, the significance of these coatings in septic reimplantation of large implants is still not sufficiently investigated. METHODS: In a retrospective analysis, 34 patients who have been treated with a modular mega-endoprosthesis after a cured bone infection of the lower limb (femur or tibia) have been evaluated. One group with 14 patients (NSCG: non silver- coated group) was supplied with the non silver- coated implants: MML München- Lübeck™ modular endoprosthesis system (AQ Implants, Ahrensburg, Germany) or MUTARS® Modular Universal Tumor And Revision System (Implantcast GmbH, Buxtehude, Germany). The other group with 20 patients (SCG: silver- coated group) was supplied with the silver- coated system of MUTARS®. In addition to the clinical findings and the patients' histories, specifically the reinfection rates, the patients' mobility was assessed using the New Mobility Score (NMS, by Parker and Palmer). RESULTS: The median follow-up period was 72 months, ranging from 6 to 267 months. The dropout rate was 5.8%. The reinfection rate after healed reinfection in SCG was 40% (8/20), in NSCG 57% (8/14), p = 0.34; α =0.05. The time for reinfection was, on average, 14 months (1-72 months) in SCG and 8 months (1-48 months) in the NSCG (p = 0.61; α =0.05). The two groups showed no differences in the NMS. CONCLUSION: With this retrospective analysis, it can be determined that the rate of reinfection of modular mega-endoprostheses on the hip and knee joint after healed periprosthetic joint infection (PJI) can be reduced by the use of silver coated implants. The time until reinfection can also be delayed by utilizing silver coated implants. Due to the low number of cases of this highly specific patient population, no statistical significance could be determined. A positive effect, however, can be assumed through the use of silver coatings in mega-endoprostheses after an infectious situation.

Effects of SARS-CoV­2 infections on inpatient mortality of geriatric patients after proximal femoral fracture surgery.

BACKGROUND: The medical challenges caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV­2) pose a tremendous burden on the healthcare system. This study aimed to analyze the effects of a SARS-CoV­2 infections or disease progression on inpatient mortality of geriatric patients after proximal femoral fracture surgery. METHODS: A retrospective analysis was conducted in all patients with a proximal femoral fracture surgically treated in an urban regional trauma center from 01/01/2020 to 01/31/2021. According to PCR test results detecting SARS-CoV­2, the patients were divided into two groups (SARS-CoV­2 positive vs. SARS-CoV­2 negative). Patient data, disease progression data, and treatment-related information were evaluated for all patients. Statistical data analysis was performed using unpaired Student's t test or non-parametric Mann-Whitney U test. RESULTS: A total of 311 patients (women: 70.4%, age: 82.0 ± 11.0 years) were included in this study. Of these 3.9% (12/311) had a positive test result for SARS-CoV­2. Significantly more deceased patients were found in the group tested positive for SARS-CoV­2 (SARS-CoV­2 positive: 41.7%, SARS-CoV­2 negative: 5.4%, p < 0.001). In addition, the number of proximal femoral fracture associated deaths correlated with the number of positive test results performed in the Clinic. The length of stay of SARS-CoV­2 COVID-19 survivors tended to be greater than in those who were tested negative (SARS-CoV­2 COVID-19 positive: 15.6 ± 13.1 days, SARS-CoV­2 COVID-19 negative: 11.5 ± 6.5 days, p = 0.683). Furthermore, a significant difference in age was found in SARS-CoV­2 survivors and SARS-CoV­2 decedents (deceased: 95.5 ± 7.5 years, alive: 83.5 ± 7.3 years, p = 0.020). CONCLUSION: The study was conducted before the introduction of SARS-CoV­2 vaccination. The results therefore refer to immune naive (unvaccinated) patients. In our study, more than 40% of all patients with proximal femoral fractures who tested positive for SARS-CoV­2 died during hospitalization. An additional, critical factor in this respect was the age of the infected patients. Nonetheless, a positive correlation was demonstrated between the mortality rate and the number of positive SARS-CoV­2 detections. Regarding the greater length of stay of patients tested positive for SARS-CoV­2, the limited transfer options (further rehabilitation, skilled nursing facility) of the infected ones can be considered as causal. Particularly the vulnerable older patients are increasingly endangered by a combination of proximal femoral fracture and SARS-CoV­2.

Biomechanical testing of different fixation techniques for intraoperative proximal femur fractures: a technical note.

Intraoperative proximal femoral fractures (IPFF) represent a rare but challenging complication of total hip arthroplasties. They usually occur as a longitudinal split. This pilot trial aimed to compare the biomechanical primary stability of different fixation techniques for IPFF. Standardised longitudinal medial split fractures of the proximal femur (type II, Modified Mallory Classification) were created in artificial osteoporotic and non-osteoporotic composite femora after implantation of a cementless femoral stem. Five different fixation techniques were compared: cerclage band, cerclage wiring with one or two wires, and lag screw fixation with one or two lag screws. A quasi-static loading protocol was applied and failure loads were evaluated. The observed median failure loads were 4192N (3982N - 5189N) for one cerclage band, 4450N (3577N - 4927N) for one cerclage wire, 5016N (4175N - 5685N) for two cerclage wires, 6085N (5000N - 8907N) for one lag screw, and 4774N (4509N - 8502N) for two lag screws. Due to the wide range of failure loads within the experimental groups, there were no observable differences between the groups. All fixation techniques provided sufficient primary stability in osteoporotic and non-osteoporotic composite bones. Further cadaveric studies with larger sample sizes may be needed to confirm the results presented here.

Factors associated with dislocation after bipolar hemiarthroplasty through an (antero-)lateral approach in elderly patients with a femoral neck fracture: a retrospective cohort study with a nested case-control subanalysis of radiographic parameters.

INTRODUCTION: Dislocations of hip hemiarthroplasty (HHA) are serious complications. The aim of the study was to identify clinical aspects and radiographic parameters of the hip that put patients at risk for dislocation after HHA for femoral neck fractures. METHODS: This retrospective analysis included elderly patients with a femoral neck fracture treated with a HHA. A lateral (90.7%) and an anterolateral (9.3%) approach was applied. On pelvic radiographs, a nested-controlled analysis was performed. Two control patients were matched to one patient suffering a dislocation with respect to age, sex, and body-mass-index (BMI). RESULTS: In 527 HHA, 10 dislocations (1.9%) were identified. In the dislocation group (DG), all patients were female (100% vs. 73.5%, p = 0.071). No significant differences between the DG and the control group (CG) were found with respect to age, body-mass-index (BMI), ASA Score, routine laboratory parameters, and comorbidity. Radiographic analysis revealed a smaller center edge angle (CEA, 39.0, IQR 33.0-42.5 vs. 43.0, IQR 41.0-46.0, p = 0.013), a more varus neck-shaft angle (NSA, 130.0, IQR 125.8-133.5 vs. 135.0, IQR 134.0-137.0, p = 0.011) of the contralateral side and a higher femoral head extrusion index (FHEI) in the DG (FHEI, 11.5, IQR 9.8-16.3 vs. 2.0 IQR 0.0-9.0, p = 0.003). In addition, a greater trochanteric fracture was associated with an increased likelihood for HHA dislocations (30.0% vs 6.0%, p = 0.022). CONCLUSION: A smaller radiographic center edge angle, a more varus neck-shaft angle of the contralateral side, a higher femoral head extrusion index and intraoperative fractures of the greater trochanter are associated with an increased risk of HHA dislocation.

Management of Modular Mega-Implant Infection of the Lower Extremity.

INTRODUCTION: Revision arthroplasty involving mega-implants is associated with a high complication rate. In particular, infection is a serious complication of revision arthroplasty of hip and knee joints and has been reported to have an average rate of 18%, and for mega-implants, the range is from 3 to 36%. This study was designed to analyze the strategy of treatment of infection of mega-endoprostheses of the lower extremities in our patient cohort, particularly the management of chronic infection. MATERIAL AND METHODS: This was a retrospective study that focused on the results of the treatment of periprosthetic infections of mega-implants of the lower extremities. We identified 26 cases with periprosthetic infections out of 212 patients with 220 modular mega-endoprostheses of the lower extremities who were treated in our department between September 2013 and September 2019. As a reinfection or recurrence, we defined clinical and microbiological recurrences of local periprosthetic joint infections after an antibiotic-free period. RESULTS: In this study, 200 cases out of 220 were investigated. The average follow-up period was approximately 18 months (6 months to 6 years). Endoprosthesis infections after implantation of mega-implants occurred in 26 cases (13%). This group comprised 2 early infections (within the first 4 weeks) and 24 chronic infections (between 10 weeks and 6 years after implantation). Nineteen cases out of the identified 26 cases with infection (73.1%) belong to the group of patients who were operated on due to major bone loss following explantation of endoprosthetic components due to previous periprosthetic joint infection. The remaining seven cases with infection comprised four cases following management of periprosthetic fracture, two cases following treatment of aseptic loosening, and one case following tumor resection. All infections were treated surgically. In all cases, the duration of continuous antibiotic treatment did not exceed 6 weeks. Both cases with early infection were treated by exchanging polyethylene inlays and performing debridement with lavage (two cases). In two (7.7%) cases with chronic infection, one-stage surgery was performed. In all remaining cases with chronic infection (22 cases; 84.6%), explantation of all components and temporary implantation of cement spacers were carried out prior to reimplantation. CONCLUSION: There is still no gold standard therapeutic regimen for the management of periprosthetic infection of mega-implants, though radical surgical debridement and lavage accompanied by systemic antibiotic therapy are the most important therapeutic tools in all cases of periprosthetic infections, regardless of the time of onset. Further studies are needed to standardize management strategies of such infections. Nevertheless, it is not uncommon for compromises to be made based on the particular condition of the individual.

Risk factors for intraoperative greater trochanteric fractures in hemiarthroplasty for intracapsular femoral neck fractures.

PURPOSE: Hemiarthroplasty is widely accepted as the treatment of choice in elderly patients with a displaced intracapsular femoral neck fracture. Intraoperative greater trochanteric fractures thwart this successful procedure, resulting in prolonged recovery, inferior outcome, and increased risk of revision surgery. Hence, this study analyzed factors potentially associated with an increased risk for intraoperative greater trochanteric fracture. METHODS: This retrospective study included 512 hemiarthroplasties in 496 patients with a geriatric intracapsular femoral neck fracture from July 2010 to March 2020. All patients received the same implant type of which 90.4% were cemented and 9.6% non-cemented. Intra- and postoperative radiographs and reports were reviewed and particularly screened for greater trochanteric fractures. RESULTS: Female patients accounted for 74% and mean age of the patients was 82.3 (± 8.7) years. 34 (6.6%) intraoperative greater trochanteric fractures were identified. In relation to patient-specific factors, only a shorter prothrombin time was found to be significantly associated with increased risk of intraoperative greater trochanteric fracture (median 96%, IQR 82-106% vs. median 86.5%, IQR 68.8-101.5%; p = 0.046). Other factors associated with greater trochanteric fracture were a shorter preoperative waiting time and changes in perioperative settings. Outcome of patients with greater trochanteric fracture was worse with significantly more surgical site infection requiring revision surgery (17.6% vs. 4.2%, p = 0.005). CONCLUSION: Prolonged prothrombin time, a shorter preoperative waiting time, and implementing new procedural standards and surgeons may be associated with an increased risk of a greater trochanteric fracture. Addressing these risk factors may reduce early periprosthetic infection which is strongly related to greater trochanteric fractures.