Development of a test system to analyze different hip fracture osteosyntheses under simulated walking

The mechanical complications of osteosyntheses after hip fractures are previously investigated by mostly static or dynamic uniaxial loading test systems. However, the physiologic loading of the hip joint during a normal gait is a multiplanar, dynamic movement. Therefore, we constructed a system to test osteosyntheses for hip fractures under physiologic multiplanar loading representative of normal gait. To evaluate the testing system, 12 femora pairs were tested under 25,000 cycles with two standard osteosyntheses (Proximal Femoral Nail Antirotation/Gamma3 Nail). For angular movement, the varus collapse to cut out (proportional to(CO)) (proportional to(CO) = 4.8 degrees +/- 2.1 degrees for blade and proportional to(CO) = 7.8 degrees +/- 3.8 degrees for screw) was the dominant failure mode, and only slight rotational angle shifts (proportional to(Rot)) (proportional to(Rot) = 1.7 degrees +/- 0.4 degrees for blade and proportional to(Rot) = 2.4 degrees +/- 0.3 degrees for screw) of the femoral head around the implant axis were observed. Angular displacements in varus direction and rotation were higher in specimens reinforced with screws. Hence, the cut out model and the migration directions showed a distinction between helical blade and hip screw. However, there were no significant differences between the different implants. The new setup is able to create clinical failures and allows to give evidence about the anchorage stability of different implant types under dynamic gait motion pattern

How Relevant Is the Parallax Effect on Low Centered Pelvic Radiographs in Total Hip Arthroplasty

The correct cup position in total hip arthroplasty (THA) is usually assessed on anteroposterior low centered pelvic radiographs, harboring the risk of misinterpretation due to projection of a three-dimensional geometry on a two-dimensional plane. In the current study, we evaluate the effect of this parallax effect on the cup inclination and anteversion in THA. In the course of a prospective clinical trial, 116 standardized low centered pelvic radiographs, as routinely obtained after THA, were evaluated regarding the impact of central beam deviation on the cup inclination and anteversion angles. Measurements of the horizontal and vertical beam offset with two different methods of parallax correction were compared with each other. Furthermore, the effect of parallax correction on the accuracy ofmeasuring the cup position was investigated. The mean difference between the two parallax correction methods was 0.2° ± 0.1° (from 0° to 0.4°) for the cup inclination and 0.1° ± 0.1° (from −0.1° to 0.2°) for the anteversion. For a typically intended cup position of a 45° inclination and 15° anteversion, the parallax effect led to a mean error of −1.5° ± 0.3° for the inclination and 0.6° ± 1.0° for the anteversion. Central beam deviation resulted in a projected higher cup inclination up to 3.7°, and this effect was more prominent in cups with higher anteversion. In contrast, the projected inclination decreased due to the parallax effect up to 3.2°, especially in cups with high inclination. The parallax effect on routinely obtained low centered pelvic radiographs is low and not clinically relevant due to the compensating effect of simultaneous medial and caudal central beam deviation

Is the rotation of the femural head a potential initiation for cutting out? A theoretical and experimental approach

We conclude the center-center position in the head of femur of any kind of lag screw or blade is to be achieved to minimize rotation of the femoral head and to prevent further mechanical complications

A systematic review of the transiliac internal fixator (TIFI) for posterior pelvic injuries

Objective: To summarize the literature on transiliac internal fixator (TIFI) indications and outcomes for treating posterior pelvic ring injuries. Methods: We searched databases for original publications in journals. Biomechanical and clinical studies using a TIFI for posterior pelvic ring injuries were considered for inclusion. The dates of publications that were included ranged from January 2000 until December 2020. Results: A total of 13 articles were reviewed, including eight clinical studies and five biomechanical tests. We found only case series and no multicenter or randomized study. The clinical studies contained data for a total of 186 cases, including indications, treatments, complications, and outcomes, with a minimum follow-up time of 12 months. All studies reported superior results according to operation time, blood loss, complication, dislocation, and union. One biomechanical test evaluated inferior results. Conclusions: The TIFI is a user-friendly and safe device to treat posterior pelvic injuries. It can also be used for acute, high-impact injuries, and fragility fractures. Nevertheless, there is no evidence concerning which types of pelvic fractures are most beneficial. Therefore, further biomechanical and clinical studies are necessary to resolve this question

Comparative analysis of non-simultaneous bilateral fractures of the proximal femur

Purpose We performed a monocenter cohort study to determine surgical revision and mortality after sustaining an initial and a non-simultaneous contralateral proximal femoral fracture. Methods We identified all patients surgically treated for a contralateral femoral fracture between 2006 and 2015. Patient demographic characteristics and follow-up were identified by our electronic database; failed information regarding revision and mortality were obtained by telephone, as well as the evaluation of the mobility for all alive patients. The endpoint of the study was set for every patient at least 2 years postoperatively. Results Within a total of 2296 patients, we identified 250 patients (10.8%) treated for a contralateral fracture. The mean interval between the two occurrences was 5.2 years and the mean age at the time of contralateral fracture was 84.4 years. Almost every third fracture occurred later than 5 years after the initial fracture, and even every tenth fracture later than 10 years. More than 50% of the patients also had dementia at this time. The total surgical revision rate was 17.2% after initial, and 20.4% after contralateral fracture, but this difference was statistically not significant (p = 0.31). However, revisions for infection or hematoma were more than twice after contralateral fracture (p = 0.006). The 1-year mortality rate was 36%, and dementia (log rank p < 0.001) and male gender (log rank p < 0.001) were significant negative predictors for the survival rate. After a mean of 42 months, the follow-up of the 67 alive patients recorded a mean Parker Score of 5.2 items. Conclusion Contralateral femoral fracture was accompanied by a higher revision and mortality rate-but patients were also 5 years older. Dementia and male gender were significant negative variables for the survival time. In the future, the highest priority will be the prophylaxis of falling to avoid or at least to decline the number of these fractures in geriatric patients

Analyse von 2000 operativ versorgten proximalen Femurfrakturen

Background. Due to demographic change, more proximal femoral fractures can be expected in the future. However, accurate growth rates as well as follow-up research extending more than 1 year postsurgery are still lacking. Materials and methods. First, we defined inclusion and exclusion criteria for the retrospective cohort study. Based on these, we collected all surgical interventions conducted between 1 January 2006 and 31 December 2015. For a total of 2000 consecutive procedures, we retrieved and analysed a total of 12 variables influencing mortality. Data were retrieved from the prospectively established database; all patients still alive were contacted by phone, and missing data were collected. The endpoint of the study was consistently set for all patients at 2 years postsurgery. Results. The follow-up rate was 100%. Growth rate increased by 74.1% over a period of 10 years. Mean age of the total population was 79.4 years, and women were predominantly affected (71.7%). Surgical treatment was based on osteosynthesis procedures (57%) using DHS, PFN, or screws, as well as on arthroplasty (43%) performing total hip arthroplasty or implanting largehead prostheses. The revision rate was 14.5%, and mortality 2 years postsurgery was 32.4%. Through a multivariate analysis (Cox regression), the following seven influence factors showed statistically significant impact on mortality: age > 82 years, male gender, CRP > 10 mg/ dl, haemoglobin < 12 g/ dl, ASA 3 or 4, dementia, and postoperative infection-but not timing of surgery. Conclusion. The growth rate of proximal femoral fractures progressed more rapidly than expected. Through a multivariate analysis, a total of six intrinsic variables were verified, which influenced the mortality. The prevention of infection-as the only additional extrinsic factor in this study-represents a more important role than early surgical treatment

Infection Versus Hematoma Following Surgical Treatment of Proximal Femoral Fractures in Geriatric Patients

Introduction: The surgical treatment of proximal femoral fractures predominantly involves geriatric patients and is associated with high morbidity and mortality. However, analyses on postoperative infections or hematoma are rare. Methods: Patients requiring surgical revision due to infection (n = 90) or hematoma (n = 77) in the postoperative phase were identified from an electronic database of 2000 consecutive patients surgically treated for proximal femoral fractures between 2006 and 2014. Demographic and clinical data were retrieved, including information on the pathogens in patients with infection. A follow-up on morbidity and mortality was conducted via telephone for at least 2 years postsurgery. Results: The follow-up rate was 100%, and the mean age was 81.9 years. The incidence rate of infection was 4.1% (90/2000), and women were commonly affected. Staphylococcus aureus and Staphylococcus epidermidis were the most commonly detected pathogens (35.5% and 25.5%, respectively). Mixed infections were observed in 15 patients, and Methicillin-resistant Staphylococcus aureus infections were observed in only 4 patients. A total of 77 (85.6%) infections occurred within 30 days postsurgery. The implant was preserved in 76 (84.4%) patients, and resection arthroplasty was required in 14 patients. Dementia and pertrochanteric fractures were significantly more common in the infection than in the hematoma group. Although infections were associated with high mortality rates for up to 2 years postsurgery, the rates did not significantly differ from those in the hematoma control group. Conclusion: One of every 2 patients who developed an infection following the surgical treatment of a proximal femoral fracture died within 2 years postsurgery. In addition, infections were significantly associated with dementia. Avoiding postoperative infection should be a high priority in the surgical treatment of proximal femoral fractures

How Relevant Is the Parallax Effect on Low Centered Pelvic Radiographs in Total Hip Arthroplasty

The correct cup position in total hip arthroplasty (THA) is usually assessed on anteroposterior low centered pelvic radiographs, harboring the risk of misinterpretation due to projection of a three-dimensional geometry on a two-dimensional plane. In the current study, we evaluate the effect of this parallax effect on the cup inclination and anteversion in THA. In the course of a prospective clinical trial, 116 standardized low centered pelvic radiographs, as routinely obtained after THA, were evaluated regarding the impact of central beam deviation on the cup inclination and anteversion angles. Measurements of the horizontal and vertical beam offset with two different methods of parallax correction were compared with each other. Furthermore, the effect of parallax correction on the accuracy ofmeasuring the cup position was investigated. The mean difference between the two parallax correction methods was 0.2° ± 0.1° (from 0° to 0.4°) for the cup inclination and 0.1° ± 0.1° (from −0.1° to 0.2°) for the anteversion. For a typically intended cup position of a 45° inclination and 15° anteversion, the parallax effect led to a mean error of −1.5° ± 0.3° for the inclination and 0.6° ± 1.0° for the anteversion. Central beam deviation resulted in a projected higher cup inclination up to 3.7°, and this effect was more prominent in cups with higher anteversion. In contrast, the projected inclination decreased due to the parallax effect up to 3.2°, especially in cups with high inclination. The parallax effect on routinely obtained low centered pelvic radiographs is low and not clinically relevant due to the compensating effect of simultaneous medial and caudal central beam deviation