The value of current diagnostic techniques in the diagnosis of fracture-related infections: Serum markers, histology, and cultures.

Although fracture-related infection (FRI) is a serious complication following bone fractures, a comprehensive definition and diagnostic criteria have only emerged in recent years. According to this consensus definition, the diagnosis of FRI is based on preoperative and intraoperative suggestive or confirmatory criteria. Serum markers, histology, and microbiological cultures are considered to play a crucial role in the FRI diagnostic pathway. However, at the time of publication of the FRI consensus definition in 2018 and its update in 2020, limited data was available on the accuracy of these diagnostic methods. This review aims to provide an overview of recent publications and discuss whether new evidence has been obtained regarding the value of these current diagnostic techniques. Meanwhile, several studies have confirmed the limited prognostic value of C-reactive protein, erythrocyte sedimentation ratio, and white blood cell count. Other serologic markers for preoperative diagnosis of FRI with promising diagnostic performance are d-dimer, plasma fibrinogen, platelet count to mean platelet volume ratio, and a risk prediction model that includes soft tissue injury type and fracture complexity in addition to blood markers. However, their true diagnostic value in daily clinical practice needs to be investigated in further studies. Data on histology in FRI diagnosis is still limited, but its potential as a confirmatory criterion seems to lie in its high specificity. Recent studies indicate that tissue culture exhibits moderate sensitivity and high specificity, with sensitivity improvements achieved by sampling of five specimens and long-term culture. Implant sonication also appears to enhance the sensitivity of culture and the detection rate of polymicrobial infections. In conclusion, the true value of diagnostic techniques is difficult to assess, in part because it is measured against a gold standard that is itself imperfect and still evolving, but also because of methodological differences in sample processing or the use of different thresholds. Nevertheless, this review has identified that the value of current diagnostic techniques is high when used in combination. To draw more accurate conclusions about the value of serum markers, histology, and culture including sonication, future studies should be prospective and utilize a greater standardization in sampling and methodological protocols.

High accuracy in lower limb alignment analysis using convolutional neural networks, with improvements needed for joint-level metrics.

OBJECTIVE: Evaluation of long-leg standing radiographs (LSR) is a standardised procedure for analysis of primary or secondary deformities of the lower limbs. Deep-learning convolutional neural networks (CNN) offer the potential to enhance radiological measurement by increasing reproducibility and accuracy. This study aims to evaluate the measurement accuracy of an automated CNN-based planning tool (mediCAD® 7.0; mediCAD Hectec GmbH) of lower limb deformities. METHODS: In a retrospective single-centre study, 164 pre- and postoperative bilateral LSRs with uni- or bilateral posttraumatic knee arthritis undergoing total knee arthroplasty (TKA) were enroled. Alignment parameters relevant to knee arthroplasty and deformity correction were analysed independently by two observers and a CNN. The intraclass correlation coefficient (ICC) was used to evaluate the accuracy between observers and the CNN, which was further evaluated using absolute deviations, limits of agreement (LoA) and root mean square error (RMSE). RESULTS: CNN evaluation demonstrated high consistency in measuring leg length (ICC > 0.99) and overall lower limb alignment measures of mechanical tibio-femoral angle (mTFA) (ICC > 0.97; RMSE < 1.1°). The mean absolute difference between angular measurements were low for overall lower limb alignment (mTFA 0.49-0.61°) and high for specific joint angles (aMPFA 3.86-4.50°). Accuracy at specific joint angles like the mechanical proximal tibial angle (MPTA) and the mechanical lateral distal femur angle (mLDFA) varied between lower limbs with deformity, with and without TKA with greatest difference for TKA (ICC 0.22-0.85; RMSE 1.72-3.65°). CONCLUSION: Excellent accuracy was observed between manual and automated measurements for overall alignment and leg length, but joint-level metrics need further improvement especially in case of TKA similar to other existing algorithms. Despite the observed deviations, the time-efficient nature of the algorithm improves the efficiency of the preoperative planning process. LEVEL OF EVIDENCE: IV.

Efficacy of Real-Time Feedback Exercise Therapy in Patients Following Total Hip Arthroplasty: Protocol for a Pilot Cluster-Randomized Controlled Trial.

BACKGROUND: Osteoarthritis of the hip joint is an increasing functional and health-related problem. The most common surgical treatment is hip replacement to reduce pain and improve function. Rehabilitation after total hip arthroplasty (THA) is not regulated in Austria and mostly depends on the patient's own initiative and possibilities. Functional deficits, such as valgus thrust of the leg, functional Trendelenburg gait, or Duchenne limp, are characteristic symptoms before and, due to the performance learning effect prior to surgery, also after the operation. Addressing these deficits is possible through neuromuscular-focused exercise therapy. The efficacy of such therapy relies significantly on the quality of performance, the frequency of exercise, and the duration of engagement. Enhancing sustainability is achievable through increased motivation and real-time feedback (RTF) on exercise execution facilitated by digital feedback systems. OBJECTIVE: This study will be performed to quantify the medium-term effectiveness of digital home exercise feedback systems on functional performance following THA. METHODS: A clinical trial with a cluster-randomized, 2-arm, parallel-group design with an 8-week intervention phase and subsequent follow-ups at 3 and 6 months postsurgery will be conducted. Feedback during exercising will be provided through a blended-care program, combining a supervised group exercise program with a self-developed digital feedback system for home exercise. In total, 70 patients will be recruited for baseline. The primary outcome parameters will be the frontal knee range of motion, pelvic obliquity, and lateral trunk lean. Secondary outcomes will be the sum scores of patient-reported outcomes and relevant kinematic, kinetic, and spatiotemporal parameters. RESULTS: The trial started in January 2024, and the first results are anticipated to be published by June 2025. RTF-supported home exercise is expected to improve exercise execution quality and therapeutic adherence compared to using paper instructions for excise guidance. CONCLUSIONS: The anticipated findings of this study aim to offer new insights into the effect of a blended-care program incorporating digital RTF on exercise therapy after unilateral THA, in addition to knowledge on the functional status 3 and 6 months postsurgery, for further improvement in the development of rehabilitation guidelines following THA. TRIAL REGISTRATION: ClinicalTrials.gov: NCT06161194; https://clinicaltrials.gov/study/NCT06161194. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): PRR1-10.2196/59755.

Biomechanical validation of novel polyurethane-resin synthetic osteoporotic femoral bones in axial compression, four-point bending and torsion.

In addition to human donor bones, bone models made of synthetic materials are the gold standard substitutes for biomechanical testing of osteosyntheses. However, commercially available artificial bone models are not able to adequately reproduce the mechanical properties of human bone, especially not human osteoporotic bone. To overcome this issue, new types of polyurethane-based synthetic osteoporotic bone models have been developed. Its base materials for the cancellous bone portion and for the cortical portion have already been morphologically and mechanically validated against human bone. Thus, the aim of this study was to combine the two validated base materials for the two bone components to produce femur models with real human geometry, one with a hollow intramedullary canal and one with an intramedullary canal filled with synthetic cancellous bone, and mechanically validate them in comparison to fresh frozen human bone. These custom-made synthetic bone models were fabricated from a computer-tomography data set in a 2-step casting process to achieve not only the real geometry but also realistic cortical thicknesses of the femur. The synthetic bones were tested for axial compression, four-point bending in two planes, and torsion and validated against human osteoporotic bone. The results showed that the mechanical properties of the polyurethane-based synthetic bone models with hollow intramedullary canals are in the range of those of the human osteoporotic femur. Both, the femur models with the hollow and spongy-bone-filled intramedullary canal, showed no substantial differences in bending stiffness and axial compression stiffness compared to human osteoporotic bone. Torsional stiffnesses were slightly higher but within the range of human osteoporotic femurs. Concluding, this study shows that the innovative polyurethane-based femur models are comparable to human bones in terms of bending, axial compression, and torsional stiffness.

Anatomic variability of the human femur and its implications for the use of artificial bones in biomechanical testing.

Aside from human bones, epoxy-based synthetic bones are regarded as the gold standard for biomechanical testing os osteosyntheses. There is a significant discrepancy in biomechanical testing between the determination of fracture stability due to implant treatment in experimental methods and their ability to predict the outcome of stability and fracture healing in a patient. One possible explanation for this disparity is the absence of population-specific variables such as age, gender, and ethnicity in artificial bone, which may influence the geometry and mechanical properties of bone. The goal of this review was to determine whether commercially available artificial bones adequately represent human anatomical variability for mechanical testing of femoral osteosyntheses. To summarize, the availability of suitable bone surrogates currently limits the validity of mechanical evaluations of implant-bone constructs. The currently available synthetic bones neither accurately reflect the local mechanical properties of human bone, nor adequately represent the necessary variability between various populations, limiting their generalized clinical relevance.

Impact of lateral cortical notching on biomechanical performance in cephalomedullary nailing for unstable pertrochanteric fractures.

PURPOSE: In pertrochanteric femur fractures the risk for fracture healing complications increases with the complexity of the fracture. In addition to dynamization along the lag screw, successful fracture healing may also be facilitated by further dynamization along the shaft axis. The aim of this study was to investigate the mechanical stability of additional axial notch dynamization compared to the standard treatment in an unstable pertrochanteric femur fracture treated with cephalomedullary nailing. METHODS: In 14 human cadaver femora, an unstable pertrochanteric fracture was stabilized with a cephalomedullary nail. Additional axial notch dynamization was enabled in half of the samples and compared against the standard treatment (n = 7). Interfragmentary motion, axial construct stiffness and load to failure were investigated in a stepwise increasing cyclic load protocol. RESULTS: Mean load to failure (1414 ± 234 N vs. 1428 ± 149 N, p = 0.89) and mean cycles to failure (197,129 ± 45,087 vs. 191,708 ± 30,490, p = 0.81) were equivalent for axial notch dynamization and standard treatment, respectively. Initial construct stiffness was comparable for both groups (axial notch dynamization 684 [593-775] N/mm, standard treatment 618 [497-740] N/mm, p = 0.44). In six out of seven specimens the additional axial dynamization facilitated interfragmentary compression, while maintaining its mechanical stability. After initial settling of the constructs, there were no statistically significant differences between the groups for either subsidence or rotation of the femoral head fragment (p ≤ 0.30). CONCLUSION: Axial notch dynamization provided equivalent mechanical stability compared to standard treatment in an unstable pertrochanteric fracture. Whether the interfragmentary compression generated by axial notch dynamization will promote fracture healing through improved fracture reduction needs to be evaluated clinically.

The infraacetabular screw versus the antegrade posterior column screw in acetabulum fractures with posterior column involvement: a biomechanical comparison.

INTRODUCTION: Traditionally, plate osteosynthesis of the anterior column combined with an antegrade posterior column screw is used for fixation of anterior column plus posterior hemitransverse (ACPHT) acetabulum fractures. Replacing the posterior column screw with an infraacetabular screw could improve the straightforwardness of acetabulum surgery, as it can be inserted using less invasive approaches, such as the AIP/Stoppa approach, which is a well-established standard approach. However, the biomechanical stability of a plate osteosynthesis combined with an infraacetabular screw instead of an antegrade posterior column screw is unknown. MATERIAL AND METHODS: Two osteosynthesis constructs were compared in a synthetic hemipelvis model with an ACPHT fracture: Suprapectineal plate + antegrade posterior column screw (APCS group) vs. suprapectineal plate + infraacetabular screw (IAS group). A single-leg stance test protocol with an additional passive muscle force and a cyclic loading of 32,000 cycles with a maximum effective load of 2400 N was applied. Interfragmentary motion and rotation of the three main fracture lines were measured. RESULTS: At the posterior hemitransverse fracture line, interfragmentary motion perpendicular to the fracture line (p < 0.001) and shear motion (p < 0.001) and at the high anterior column fracture line, interfragmentary motion longitudinal to the fracture line (p = 0.017) were significantly higher in the IAS group than in the APCS group. On the other hand, interfragmentary motion perpendicular (p = 0.004), longitudinal (p < 0.001) and horizontal to the fracture line (p = 0.004) and shear motion (p < 0.001) were significantly increased at the low anterior column fracture line in the APCS group compared to the IAS group. CONCLUSIONS: Replacing the antegrade posterior column screw with an infraacetabular screw is not recommendable as it results in an increased interfragmentary motion, especially at the posterior hemitransverse component of an ACPHT fracture.

Evaluation of Meniscal Load and Load Distribution in the Sound Canine Stifle at Different Angles of Flexion.

OBJECTIVES: The aim of the study was to investigate the contact mechanics and kinematic changes in the stifle in different standing angles. STUDY DESIGN: We performed a biomechanical ex vivo study using pairs of canine cadaver hindlimbs. Motion sensors were fixed to the tibia and the femur for kinematic data acquisition. Pressure mapping sensors were placed between the femur and both menisci. Thirty percent bodyweight was applied to the limbs with the stifle in 125, 135, or 145 degrees of extension. RESULTS: Stifle flexion angle influences femoromeniscal contact mechanics significantly. The load on both menisci was significantly higher for 125 and 135 degrees in comparison to 145 degrees. Additionally, the center of force was located significantly more caudal when comparing 125 to 145 degrees in the medial meniscus as well as in both menisci combined. CONCLUSION: The angle of knee flexion significantly impacts the contact mechanics between the femur and the meniscus. As the knee flexes, the load on both menisci increases.

Preservation of the heart in ancient Egyptian mummies: A computed tomography investigation with focus on the myocardium.

The ancient Egyptians considered the heart to be the most important organ. The belief that the heart remained in the body is widespread in the archeological and paleopathological literature. The purpose of this study was to perform an overview of the preserved intrathoracic structures and thoracic and abdominal cavity filling, and to determine the prevalence and computed tomography (CT) characteristics of the myocardium in the preserved hearts of ancient Egyptian mummies. Whole-body CT examinations of 45 ancient Egyptian mummies (23 mummies from the Ägyptisches Museum und Papyrussammlung, Berlin, Germany, and 22 mummies from the Museo Egizio, Turin, Italy) were systematically assessed for preserved intrathoracic soft tissues including various anatomical components of the heart (pericardium, interventricular septum, four chambers, myocardium, valves). Additionally, evidence of evisceration and cavity filling was documented. In cases with identifiable myocardium, quantitative (measurements of thickness and density) and qualitative (description of the structure) assessment of the myocardial tissue was carried out. Heart structure was identified in 28 mummies (62%). In 33 mummies, CT findings demonstrated evisceration, with subsequent cavity filling in all but one case. Preserved myocardium was identified in nine mummies (five male, four female) as a mostly homogeneous, shrunken structure. The posterior wall of the myocardium had a mean maximum thickness of 3.6 mm (range 1.4-6.6 mm) and a mean minimum thickness of 1.0 mm (range 0.5-1.7 mm). The mean Hounsfield units (HU) of the myocardium at the posterior wall was 61 (range, 185-305). There was a strong correlation between the HU of the posterior wall of the myocardium and the mean HU of the muscles at the dorsal humerus (R = 0.77; p = 0.02). In two cases, there were postmortem changes in the myocardium, most probably due to insect infestation. To our knowledge, this is the first study to investigate the myocardium systematically on CT scans of ancient Egyptian mummies. Strong correlations between the densities of the myocardium and skeletal muscle indicated similar postmortem changes of the respective musculature during the mummification process within individual mummies. The distinct postmortem shrinking of the myocardium and the collapse of the left ventriclular cavity in several cases did not allow for paleopathological diagnoses such as myocardial scarring.

Distal femur fractures: basic science and international perspectives.

Distal femur fractures are challenging injuries to manage, and complication rates remain high. This article summarizes the international and basic science perspectives regarding distal femoral fractures that were presented at the 2022 Orthopaedic Trauma Association Annual Meeting. We review a number of critical concepts that can be considered to optimize the treatment of these difficult fractures. These include biomechanical considerations for distal femur fixation constructs, emerging treatments to prevent post-traumatic arthritis, both systemic and local biologic treatments to optimize nonunion management, the relative advantages and disadvantages of plate versus nail versus dual-implant constructs, and finally important factors which determine outcomes. A robust understanding of these principles can significantly improve success rates and minimize complications in the treatment of these challenging injuries.

Open the pores - Polydimethylsiloxane influences the porous structure of cancellous bone surrogates for biomechanical testing of osteosyntheses.

Synthetic materials used for valid and reliable implant testing and design should reflect the mechanical and morphometric properties of human bone. Such bone models are already available on the market, but they do not reflect the population variability of human bone, nor are they open-celled porous as human bone is. Biomechanical studies aimed at cementing the fracture or an implant cannot be conducted with them. The aim of this study was to investigate the influence of a cell stabilizer on polyurethane-based cancellous synthetic bone in terms of morphology, compressive mechanics, and opening of the cancellous bone structure for bone cement application. Mechanical properties of cylindrical specimens of the bone surrogates were determined by static compression tests to failure. Furthermore, a morphometric analysis was performed using microcomputed tomography. To prove the open-cell nature of the bone surrogates, an attempt was made to apply bone cement. Effects on the mechanical properties of the polyurethane-based bone surrogates were observed by the addition of polydimethylsiloxane. All mechanical parameters like Young's modulus, ultimate stress and yield stress increased statistically significantly with increasing amounts of cell stabilizer (all p > 0.001), except for yield stress. The analysis of morphometric parameters showed a decrease in trabecular thickness, spacing and connectivity density, which was accompanied by an increase in trabecular number and an increase in pore size. The open-cell nature was proven by the application and distribution of bone cement in specimens with stabilizer, which was visualized by X-ray. In conclusion, the results show that by adding a cell stabilizer, polyurethane-based cancellous bone substrates can be produced that have an open-cell structure similar to human bone. This makes these bone surrogates suitable for biomechanical testing of osteosyntheses and for osteosynthesis cementation issues.

Tibial tuberosity-trochlear groove distance is significantly decreased by medial closing wedge distal femoral osteotomy.

PURPOSE: While medial closing wedge distal femoral osteotomy (MCWDFO) has been used to address patella instability combined with valgus malalignment, its impact on patellofemoral parameters remains uncharted. Hence, this study seeks to establish a three-dimensional (3D) planning of MCWDFO and measure its effect on the tibial tubercle - trochlear groove distance (TTTG) through simulation and calculation. METHODS: MCWDFO with a stepwise increment of one-degree varisation (1°-15°) was performed on 3D surface models of 14 lower extremities with valgus malalignment and 24 lower extremities with neutral alignment of the lower limb, resulting in a total of 608 simulations. Anatomic landmarks were employed to measure hip-knee-ankle angle (HKA), TTTG, and femoral torsion for each simulation. A mathematical formula was adopted to calculate TTTG changes following MCWDFO, and subsequently the mean simulated and calculated TTTG values were compared. Following a standardised protocol, MCWDFO was performed without rotational changes. RESULTS: MCWDFO exhibited an almost linear reduction in TTTG, at a rate of approximately -1.05 ± 0.13 mm per 1° of varisation, demonstrating a strong negative correlation (R = -0.83; p < 0.001). Limb alignment did not exert an influence on TTTG change; however, it correlated with tibial plateau width. The mean difference between the simulated and calculated TTTG values amounted to 0.03 ± 0.03 mm per 1° varisation (p < 0.001). CONCLUSION: The TTTG distance is linearly reduced by 1.05 mm for every 1° of varisation within the varus correction range of 0°-15° during MCWDFO. Patients with combined valgus and patellar instability may benefit from MCWDFO due to frequently pathological TTTG. LEVEL OF EVIDENCE: Level III, descriptive laboratory study.

Undersizing of the tibial component in Oxford unicompartmental knee arthroplasty (UKA) increases the risk of periprosthetic fractures.

INTRODUCTION: Tibial periprosthetic fractures (TPF) after unicompartmental knee arthroplasty (UKA) are a rare condition that affects about 1% of cases. Known risk factors include age, sex, body mass index (BMI), and bone density, as well as surgical technique and prosthesis design. The purpose of the study was to determine if undersizing of the tibial component in relation to the femoral component increases the risk of tibial periprosthetic fractures. MATERIAL AND METHODS: Over a 6-year-period 1542 patients with cemented (n = 363) and uncemented (n = 1179) medial UKA were retrospectively evaluated. Tibial periprosthetic fractures were identified and classified, and epidemiologic data were documented at follow-up. Undersizing was defined as a smaller tibial component compared to the femoral implant. The association of potential risk factors for TPF with the incidence of TPF was investigated with binominal logistic regression. RESULTS: Fourteen patients (0.9%) suffered from TPF at a median of 1 month after surgery. The mean follow-up period was 5.9 ± 1.7 years. Fractures were more common in cases with undersized tibial components [odds ratio (OR) 3.2, p < 0.05]. Furthermore, older age (OR 1.1, p < 0.05) and female sex (OR 6.5, p < 0.05) were identified as significant risk factors, while BMI (p = 0.8) and cemented implantation (p = 0.2) had no effect on fracture rate. Revision surgery included open reduction and internal fixation or conversion to total knee arthroplasty. CONCLUSIONS: Undersizing of implant sizes in UKA increases the risk for TPF especially in patients with small tibial implants. Therefore, mismatched implants should be avoided for UKA particularly when risk factors like obesity, older age, or female gender are present. Tibial periprosthetic fractures were successfully treated by open reduction and internal fixation or conversion to total knee arthroplasty.

[Possibilities and limits of intraoperative 2D imaging in trauma surgery]. / Möglichkeiten und Grenzen der intraoperativen 2D-Bildgebung in der Unfallchirurgie.

BACKGROUND: The two-dimensional (2D) imaging represents an essential and cost-effective component of intraoperative position control in fracture stabilization, even in the era of new three-dimensional (3D) imaging capabilities. OBJECTIVE: The aim of the present study, in addition to a current literature review, was to examine whether the intraoperative use of 2D images leads to a quality of fracture reduction comparable to postoperative computed tomographic (CT) analysis including 3D reconstructions. MATERIAL AND METHODS: A comparative retrospective analysis of intraoperative 2D and postoperative 3D image data was performed on 21 acetabular fractures stabilized via a pararectus approach according to an established protocol using the Matta criteria. RESULTS: The assessment of fracture reduction in intraoperative fluoroscopy compared with postoperative CT revealed a difference only in one case with respect to the categorization of the joint step reduction in the main loading zone. CONCLUSION: In the intraoperative use of 2D imaging for fracture treatment it is important to select the correct adjustment planes taking the anatomical conditions into account in order to achieve optimum assessability. In this way, the reduction result can be adequately displayed in fluoroscopy and is also comparable to the postoperative CT control. In addition, depending on the findings, optional intraoperative dynamic fluoroscopic assessment can have a direct influence on the further surgical procedure.

[Movement analysis in spinal cord injuries : Assistance in clinical decision making]. / Bewegungsanalyse bei Querschnittverletzungen : Hilfestellung in der klinischen Entscheidungsfindung.

For motor incomplete spinal cord injured patients, improvement of walking function is an important aim in the rehabilitation program. In specialized treatment centers, the 6­minute walking test, the 10-meter walking test or the timed-up-and-go test are used as an assessment tool to determine walking ability, but these tests are not able to assess the quality of gait. Marker-based movement analysis can be used as a reliable method to evaluate the gait pattern. This allows an objective assessment of gait quality over time or can be used to support therapy planning. The benefit of such an analysis is presented by means of two case studies.

The value of sonication in the differential diagnosis of septic and aseptic femoral and tibial shaft nonunion in comparison to conventional tissue culture and histopathology: a prospective multicenter clinical study.

BACKGROUND: Septic and aseptic nonunion require different therapeutic strategies. However, differential diagnosis is challenging, as low-grade infections and biofilm-bound bacteria often remain undetected. Therefore, the examination of biofilm on implants by sonication and the evaluation of its value for differentiating between femoral or tibial shaft septic and aseptic nonunion in comparison to tissue culture and histopathology was the focus of this study. MATERIALS AND METHODS: Osteosynthesis material for sonication and tissue samples for long-term culture and histopathologic examination from 53 patients with aseptic nonunion, 42 with septic nonunion and 32 with regular healed fractures were obtained during surgery. Sonication fluid was concentrated by membrane filtration and colony-forming units (CFU) were quantified after aerobic and anaerobic incubation. CFU cut-off values for differentiating between septic and aseptic nonunion or regular healers were determined by receiver operating characteristic analysis. The performances of the different diagnostic methods were calculated using cross-tabulation. RESULTS: The cut-off value for differentiating between septic and aseptic nonunion was ≥ 13.6 CFU/10 ml sonication fluid. With a sensitivity of 52% and a specificity of 93%, the diagnostic performance of membrane filtration was lower than that of tissue culture (69%, 96%) but higher than that of histopathology (14%, 87%). Considering two criteria for infection diagnosis, the sensitivity was similar for one tissue culture with the same pathogen in broth-cultured sonication fluid and two positive tissue cultures (55%). The combination of tissue culture and membrane-filtrated sonication fluid had a sensitivity of 50%, which increased up to 62% when using a lower CFU cut-off determined from regular healers. Furthermore, membrane filtration demonstrated a significantly higher polymicrobial detection rate compared to tissue culture and sonication fluid broth culture. CONCLUSIONS: Our findings support a multimodal approach for the differential diagnosis of nonunion, with sonication demonstrating substantial usefulness. LEVEL OF EVIDENCE: Level 2 Trial registration DRKS00014657 (date of registration: 2018/04/26).

Risk of Interprosthetic Femur Fracture Is Associated with Implant Spacing-A Biomechanical Study.

BACKGROUND: Ipsilateral revision surgeries of total hip or knee arthroplasties due to periprosthetic fractures or implant loosening are becoming more frequent in aging populations. Implants in revision arthroplasty usually require long anchoring stems. Depending on the residual distance between two adjacent knee and hip implants, we assume that the risk of interprosthetic fractures increases with a reduction in the interprosthetic distance. The aim of the current study was to investigate the maximum strain within the femoral shaft between two ipsilateral implants tips. METHODS: A simplified physical model consisting of synthetic bone tubes and metallic implant cylinders was constructed and the surface strains were measured using digital image correlation. The strain distribution on the femoral shaft was analyzed in 3-point- and 4-point-bending scenarios. The physical model was transferred to a finite element model to parametrically investigate the effects of the interprosthetic distance and the cortical thickness on maximum strain. Strain patterns for all parametric combinations were compared to the reference strain pattern of the bone without implants. RESULTS: The presence of an implant reduced principal strain values but resulted in distinct strain peaks at the locations of the implant tips. A reduced interprosthetic distance and thinner cortices resulted in strain peaks of up to 180% compared to the reference. At low cortical thicknesses, the strain peaks increased exponentially with a decrease in the interprosthetic distance. An increasing cortical thickness reduced the peak strains at the implant tips. CONCLUSIONS: A minimum interprosthetic distance of 10 mm seems to be crucial to avoid the accumulation of strain peaks caused by ipsilateral implant tips. Interprosthetic fracture management is more important in patients with reduced bone quality.

Evidence on treatment of clavicle fractures.

Depending on the severity of the injury and the involvement of the soft tissue envelope, clavicle fractures can be treated operatively or non-operatively. In the past, displaced fractures of the clavicle shaft in adults have been treated non-operatively. However, the rate of nonunion following non-operative treatment seems to be higher than previously reported. In addition, publications reporting better functional outcomes following operative treatment are increasing. In recent years this has led to a paradigm shift towards an increase of operative fracture treatment. The aim of this review article was to summarize the currently available evidence on the treatment of clavicle fractures. Classifications, indications, and treatment options for different fracture patterns of the medial, midshaft, and lateral clavicles are presented and discussed.

Meniscal Load and Load Distribution in the Canine Stifle after Modified Tibial Tuberosity Advancement with 9 mm and 12 mm Cranialization of the Tibial Tuberosity in Different Standing Angles.

OBJECTIVES: The aim of this study was to investigate the kinetic and kinematic changes in the stifle after a modified tibial tuberosity advancement (TTA) with 9 and 12 mm cranialization of the tibial tuberosity in different standing angles. STUDY DESIGN: Biomechanical ex vivo study using seven unpaired canine cadaver hindlimbs. Sham TTA surgery was performed. Motion sensors were fixed to the tibia and the femur for kinematic data acquisition. Pressure mapping sensors were placed between femur and both menisci. Thirty percent body weight was applied to the limbs with the stifle in 135 or 145 degrees of extension. Each knee was tested in 135 degrees with intact cranial cruciate ligament (CCL) and deficient CCL with 12 mm cranialization of the tibial tuberosity in 135 and 145 degrees of extension. The last two tests were repeated with 9 mm. RESULTS: Transection of the CCL altered kinematics and kinetics. Tibial tuberosity advancement with 12 mm cranialization sufficiently restored stifle kinematics in 135 and 145 degrees but 9 mm TTA failed to do so in 135 degrees. The same effects were seen for internal rotation of the tibia. After TTA, a significant reduction in the force acting on both menisci was detected. CONCLUSION: Tibial tuberosity advancement could restore stifle kinematics and meniscal kinetics after transection of the CCL ex vivo in the present study. Tibial tuberosity advancement reduced the contact force ratio on both menisci significantly. No changes of peak pressure and peak pressure location occurred following TTA under any of the tested experimental settings. Increased stifle extension (145 degrees) might lead to more stability, contradictory to biomechanical theory.