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.

Comparison of different intraoperative reduction monitoring methods in a cadaveric intraarticular calcaneal fracture model: 3D scan vs arthroscopy vs nanoscopy.

AIMS: Visualization of the subtalar joint surface in surgical management of calcaneal factures remains a big challenge and anatomic reduction of the articular surface is essential for a good clinical outcome. We hypothesize that video-assistance can provide superior fracture reduction compared to fluoroscopy and that nanoscopy (NSC) achieves more extensive visualization compared to fracturoscopy (FSC). METHODS: Ten human cadaveric feet with artificially pre-fractured intraarticular calcaneal fractures with involvement of the posterior facet were treated via a minimal invasive subtalar approach. After initial control of reduction by 2D fluoroscopy, the reduction was further analyzed intraoperatively by FSC and NSC. 3D Scan served as gold standard control of reduction. Need of revision of reduction after the different visualization techniques was recorded and the extent of visualization of the subtalar joint surface in the medio-lateral dimension was compared for FSC and NSC. To quantify access and visualization of the medial and posterior facet, a depth gauge was used to measure from laterally at the clinically widest portion of the calcaneus targeted to the sustentaculum tali. The distance in millimetres was referred to the complete medio-lateral distance seen on paracoronal CT at the widest portion of the calcaneus. RESULTS: Fracture analysis in preoperative CT-scans according to Sanders classification revealed four type IC, two IIA, three IIC and one IIIAC fractures. Mean visualization of the medial and posterior facet was significantly improved with NSC (30.4 ± 3.78 mm) compared to FSC (23.6 ± 6.17 mm) (p = 0.008). An imperfect reduction requiring revision was more often required with NSC compared to FSC. Insufficient reduction using video-assistance was found in two cases. CONCLUSION: In order to optimize subtalar joint reduction and congruency, video-assisted techniques, especially NSC, provide superior visualization and thus can improve reduction in the surgical treatment of intraarticular calcaneal fractures.

Association of medial collateral ligament complex injuries with anterior cruciate ligament ruptures based on posterolateral tibial plateau injuries.

BACKGROUND: The combined injury of the medial collateral ligament complex and the anterior cruciate ligament (ACL) is the most common two ligament injury of the knee. Additional injuries to the medial capsuloligamentous structures are associated with rotational instability and a high failure rate of ACL reconstruction. The study aimed to analyze the specific pattern of medial injuries and their associated risk factors, with the goal of enabling early diagnosis and initiating appropriate therapeutic interventions, if necessary. RESULTS: Between January 2017 and December 2018, 151 patients with acute ACL ruptures with a mean age of 32 ± 12 years were included in this study. The MRIs performed during the acute phase were analyzed by four independent investigators-two radiologists and two orthopedic surgeons. The trauma impact on the posterolateral tibial plateau and associated injuries to the medial complex (POL, dMCL, and sMCL) were examined and revealed an injury to the medial collateral ligament complex in 34.4% of the patients. The dMCL was the most frequently injured structure (92.2%). A dMCL injury was significantly associated with an increase in trauma severity at the posterolateral tibial plateau (p < 0.02) and additional injuries to the sMCL (OR 4.702, 95% CL 1.3-133.3, p = 0.03) and POL (OR 20.818, 95% CL 5.9-84.4, p < 0.0001). Isolated injuries to the sMCL were not observed. Significant risk factors for acquiring an sMCL injury were age (p < 0.01) and injury to the lateral meniscus (p < 0.01). CONCLUSION: In about one-third of acute ACL ruptures the medial collateral ligament complex is also injured. This might be associated with an increased knee laxity as well as anteromedial rotational instability. Also, this might be associated with an increased risk for failure of revision ACL reconstruction. In addition, we show risk factors and predictors that point to an injury of medial structures and facilitate their diagnosis. This should help physicians and surgeons to precisely diagnose and to assess its scope in order to initiate proper therapies. With this in mind, we would like to draw attention to a frequently occurring combination injury, the so-called "unlucky triad" (ACL, MCL, and lateral meniscus). Level of evidence Level III Retrospective cohort study.

Epidemiology and socioeconomic consequences of work-related pelvic and acetabular fractures recorded in the German Social Accident Insurance.

INTRODUCTION: Pelvic and acetabular fractures can result from work-related accidents and frequently require lengthy medical treatments. Consequently, high medical costs as well as delayed or absent return to work can be the consequence. Therefore, we aimed to study the socioeconomic consequences of work-related pelvic and acetabular fractures. MATERIALS AND METHODS: This retrospective study investigated work-related pelvic and acetabular fractures recorded in the German Social Accident Insurance in 2011 and 2017, in terms of age, sex, type of accident, duration of incapacity to work, reductions in earning capacity, costs for outpatient and inpatient treatment and costs for pension and severance pay. RESULTS: Among a total of 606 injuries in 2011 and 619 injuries in 2017, male patients and patients between 40 and 65 years were predominantly affected. Acetabular fractures caused higher rates of long absence from work of 6-12 months (2011: 24.7% vs. 9.5-16.9%; 2017: 26.1% vs. 6.1-11.0%) and >12 months (2011: 15.8% vs. 9.8-10.2%; 2017: 13.3% vs. 1.9-8.2%) as well as more cases with a reduction in earning capacity of at least 20% (2011: 61 vs. ≤27 cases; 2017: 39 vs. ≤12 cases) compared to pelvic ring fractures. The total costs for pelvic ring and acetabular fractures in the German social accident insurances amounted € 18,726,630 and € 9637,189 in the periods 2011-2020 and 2017-2020, respectively. The average costs per case for treatment and rehabilitation until 2020 was € 19,079 for injuries from 2011 and € 13,629 for injuries from 2017. Acetabular fractures were found to be the most cost-intensive injuries compared to anterior, posterior or complex pelvic ring fractures. CONCLUSIONS: Work-related pelvic and especially acetabular fractures have a considerable socioeconomic impact in the German Social Accident Insurance. Measures to prevent work-related accidents and to improve treatment of pelvic injuries can help to reduce their socioeconomic burden.

A Register Analysis after Tibial Plateau Fracture in Statutory Accident Insurance. / Ergebnisse und Kosten nach Tibiakopffraktur in der gesetzlichen Unfallversicherung ­ eine Registeranalyse.

OBJECTIVE: To analyse the results after tibial plateau fractures with a focus on socioeconomic consequences. METHODS: On the basis of the data from the rehabilitation documentation of the German Statutory Accident Insurance (DGUV) on tibial plateau fractures (Code 83), a retrospective anonymised evaluation of the injuries which occurred in 2010 and 2016 was carried out. The registry data allowed subdivision into 3 groups: Medial, lateral and bicondylar tibial plateau fractures. The data have been analysed with regard to the following parameters: age, gender, treatment, time of return to work (AU), costs per case, total costs, workers compensation (MdE) and total payments. RESULTS: The analysis includes 1046 isolated tibial plateau fractures for 2010 and 1072 for 2016. In 2016, 798 fractures could be assigned to the medial, lateral or bicondylar fracture groups. In 551 cases, both condyles were involved. In another 221 cases, the lateral plateau and in 26 the medial plateau was injured. There were 476 (59.7%) men and 322 (40.4%) women. The mean age was 43.4 (SD ± 16.7) years with a peak of 180 cases in the 55-60 year subgroup and 98 aged 15-20 years. The mean age of the cases with isolated lateral plateau involvement was 48.1 (SD ± 13.8) and was 47.5 (SD ± 16.6) in those with medial plateau fractures and 41.4 (SD ± 17.2) years in the subgroup with bicondylar patterns. The mean time of return to work was 39.4 (SD ± 25.3) weeks for the bicondylar tibial plateau fractures, 28.1 (SD ± 27.2) weeks for the medial and 24.5 (SD ± 22.8) weeks for the lateral groups. For the 2016 group, the mean costs were 5212 € for outpatient, 10358 € for inpatient and 7622 € for rehab costs per case (total costs over three years of 4247443 € for outpatient and 7506508 € for acute inpatient treatment). The highest costs per case were caused by the inpatient acute treatment of bicondylar tibial plateau fractures, at a mean of 22292 €. 17.6% of the 2016 casualty group resulted in compensation of at least 20%. The treatment costs for the 2010 group over 9 years (2010-2019) amounted to 4190855 € for outpatient treatments and € 9565313 for inpatient treatments. In addition, compensations of 8632448 € and lump-sum payments of 483289 € were paid from 2010 to 2019. Over a period of 9 years, 456 (66%) of 692 patients needed another in patient follow-up treatment. A total of 51% (n = 353) needed these treatments within the first year. CONCLUSION: Tibial plateau fractures, in particular bicondylar tibial plateau fractures, show long-term, cost-intensive healing processes with reduced occupational capacity. Tibial plateau fractures are of economic importance in the statutory accident insurance in the long term. Preventive measures, optimal care and rehabilitation are therefore essential, together with innovative research to improve clinical outcomes.

Anterolateral versus modified posterolateral approach for tibial plateau fractures with involvement of the posterior column: a cadaveric study.

INTRODUCTION: The aim of this study was to compare the reduction quality of the anterolateral (AL) and modified posterolateral approach (PL) in lateral tibial plateau fractures involving the posterior column and central segments. METHODS: Matched pairs of pre-fractured cadaveric tibial plateau fractures were treated by either AL approach (supine position) or PL approach (prone position). Reduction was controlled by fluoroscopy and evaluated as satisfying or unacceptable. Afterwards, the reduction was examined by 3D scan. RESULTS: 10 specimens (3 pairs 41B3.1, 2 pairs 41C3.3) were evaluated. PL approach achieved significantly (p 0.00472) better fracture reduction results (0.4 ± 0.7 mm) of the posterior column compared to the AL group (2.1 ± 1.4 mm). Fracture steps involving the central area of the lateral plateau were insufficiently reduced after fluoroscopy using both approaches. CONCLUSION: Optimal reduction of displaced tibial plateau fractures involving the posterolateral column necessitates a posterior approach, which can be conducted in prone or lateral positioning. The anterolateral approach is indicated in fractures with minor displacement of the posterolateral rim but fracture extension in the latero-central segments. In these cases, an additional video-assisted reduction or extended approaches are helpful.

Biomechanical in vitro analysis of a novel flexible implant for pubic symphysis disruption using an ultra-high molecular weight polyethylene fiber cord.

BACKGROUND: Plate osteosynthesis depicts the gold standard to surgically treat pubic symphysis disruptions. However, high rates of implant failure after plate osteosynthesis are reported, probably because of the iatrogenic arthrodesis of this fibrocartilaginous joint. Therefore, flexible implants for treatment of pubic symphysis disruptions appear to be a sensible solution. METHODS: In this biomechanical screening study, we designed and investigated a flexible implant, which consists of two plates connected with an ultra-high molecular weight polyethylene fiber cord. We mechanically tested eye splices as a possible fixation method of the cords by performing tensile load to failure tests. Afterwards, we developed a biomechanically appropriate plate design and cord routing between the plates. Finally, we biomechanically tested the flexible implant under tensile and shear loading until failure. FINDINGS: When fixing a 1 mm ultra-high molecular weight polyethylene fiber cord with eye splices, a load at failure of 1570.74 N was detected under tensile loading. None of the eye splices failed but the cords itself ruptured. The load at failure of the designed cord routing in criss-cross technique and fixation within the plates amounts 4742.09 N under tensile and 2699.77 N under shear load. INTERPRETATION: We developed a novel flexible implant for repair of pubic symphysis disruptions using ultra-high molecular weight polyethylene fiber cords connected to osteosynthesis plates. We identified eye splices as a mechanically optimal fixation method and proved that the ultra-high molecular weight polyethylene fiber cord routing and fixation of the flexible implant clearly withstands physiological forces acting on the pubic symphysis.

Biomechanical analysis of fixation methods in acetabular fractures: a systematic review of test setups.

PURPOSE: Optimal anatomical reduction and stable fixation of acetabular fractures are important in avoiding secondary dislocation and osteoarthritis. Biomechanical studies of treatment options of acetabular fractures aim to evaluate the biomechanical properties of different fixation methods. As the setup of the biomechanical test can influence the experimental results, this review aimed to analyze the characteristics, comparability and clinical implications of studies on biomechanical test setups and finite element analyses in the fixation of acetabular fractures. METHODS: A systematic literature research was conducted according to the PRISMA guidelines, using the PubMed/MEDLINE and Web of Science databases. 44 studies conducting biomechanical analyses of fixation of acetabular fractures were identified, which met the predefined inclusion and exclusion criteria and which were published in English between 2000 and April 16, 2021. The studies were analyzed with respect to distinct parameters, including fracture type, material of pelvis model, investigated fixation construct, loading direction, loading protocol, maximum loading force, outcome parameter and measurement method. RESULTS: In summary, there was no standardized test setup within the studies on fixation constructs for acetabular fractures. It is therefore difficult to compare the studies directly, as they employ a variety of different test parameters. Furthermore, the clinical implications of the biomechanical studies should be scrutinized, since several test parameters were not based on observations of the human physiology. CONCLUSION: The limited comparability and restricted clinical implications should be kept in mind when interpreting the results of biomechanical studies and when designing test setups to evaluate fixation methods for acetabular fractures.

Stresses and deformations of an osteosynthesis plate in a lateral tibia plateau fracture.

This study has the aim to investigate the strain and stress in an anterolateral locking plate applied for the fixation of a lateral split fracture. To simulate a complex fracture situation, three segments were separated. With a FEM analysis, representative places for strain and stress measurement were determined. A locked osteosynthesis plate was instrumented with strain gauges and tested on a fractured and a non-fractured Saw Bone model. To simulate different loading situations, four different points of force application, from the center of the condyles to a 15 mm posterior position, were used with a medial-lateral load distribution of 60:40. The simulations as well as the biomechanical tests demonstrated that two deformations dominate the load on the plate: a bending into posterior direction and a bulging of the plate head. Shifting the point of application to the posterior direction resulted in increasing maximum stress, from 1.16 to 6.32 MPa (FEM analysis) and from 3.04 to 7.00 MPa (biomechanical study), respectively. Furthermore, the comparison of the non-fractured and fractured models showed an increase in maximum stress by the factor 2.06-2.2 (biomechanical investigation) and 1.5-3.3 (FEM analysis), respectively.

[Pseudarthrosis after bony avulsion fracture of the posterior cruciate ligament]. / Pseudarthrose nach knöchernem Ausriss des hinteren Kreuzbandes.

BACKGROUND: Tibial bony avulsion fractures of the posterior cruciate ligament (PCL) are rare injuries and in certain cases a delayed healing or non-union can occur under conservative treatment. OBJECTIVE: Presentation of the clinical result of patients with pseudarthrosis who were secondarily operated on after bony avulsion of the PCL. MATERIAL AND METHODS: The study included all patients who were operated on since 2010 for reasons of delayed or non-union PCL avulsion fracture in this clinic. Standardized questionnaires and follow-up documentation, e.g. visual analog scale (VAS), International Knee Documentation Committee (IKDC), Lysholm and Tegner scores were used and a magnetic resonance imaging (MRI) monitoring of the injured knee was carried out. RESULTS: A total of 5 patients aged from 30 to 63 years (3 male, 2 female) were identified with mainly persisting flexion pain and instability under conservative treatment and secondary surgery of the knee. In the follow-up of 4 patients good results could be achieved (IKDC health condition 81/subjective assessment 76) after minimally invasive direct screw reduction with consolidation of the fracture zone; however, there was a slight residual dorsal instability. DISCUSSION: The secondary operative treatment of pseudarthrosis of bony PCL injuries led to good clinical results. Due to the detectable residual instability the authors are of the opinion that the indications for primary osteosynthesis in the acute phase should be generously considered. This must still be corroborated in studies with larger case numbers. CONCLUSION: The indications for MRI diagnostics should be generously considered, Smoking appears to be associated with an increased risk of pseudarthrosis. Good results can be achieved with a minimally invasive posterior screw approach, even after a delay.