Is there a correlation between pelvic incidence and orientation of the acetabulum? An analysis based on a three-dimensional statistical model of the pelvic ring.

The pelvic ring is a complex anatomical structure building up the connection between the trunk and the legs. Whilst there is a broad discussion in the literature about the dynamic interaction between spine, pelvis and the hip joints, there is still little information about the relation and interaction of the constant pelvic parameters. Based on a three-dimensional (3D) statistical model consisting of 150 uninjured and bony healthy pelves (100 Europeans, 50 Japanese; 81 males, 69 females; average age 74.3 years ± 17.5 years) an evaluation of pelvic incidence (PI) and acetabular orientation in anteversion and inclination was performed and potential correlations of these intraindividual constant parameters were investigated. Pelvic incidence is defined as the angle between the perpendicular to the sacral plate at its midpoint and the line connecting this point to the middle axis of the femoral heads. Acetabular anteversion is defined as the angle between the perpendicular to the best-fit plane on the acetabular rim and the coronal plane measured in strict lateral view. Acetabular inclination is defined as the angle between the perpendicular to the best-fit plane on the acetabular rim and the sagittal plane in strict frontal view. Data were further analysed with regard to different subgroup's age, sex and ethnicity. A positive correlation between PI and acetabular anteversion could be demonstrated. Further, PI and also the acetabular parameters anteversion and inclination were found to be significantly higher in the European individuals than in the Asian. The results of the present study demonstrate a relation between the anatomical configuration of the constant pelvic parameters building up the connection points to the next proximal respectively caudal skeleton section. The findings might lead to more comprehensive treatment strategies in case of trauma or degenerative pathologies of the pelvis in the future.

Asymmetry of the pelvic ring evaluated by CT-based 3D statistical modeling.

The human pelvis is a complex anatomical structure that consists of the innominate bones, sacrum and coccyx to form the pelvic ring. Even though considered to be a symmetric entity, asymmetry of the pelvic ring (APR) might occur to alter its anatomy, function, or biomechanics or to impact assessment and treatment of clinical cases. APR and its assessment is complicated by the intricate anatomy of the pelvic ring. There is only limited information and understanding about APR with no established evaluation methods existing. The objective of the present study was to adopt CT-based 3D statistical modeling and analysis to assess APR within the complex anatomy of the pelvic ring. We were interested to establish a better understanding of APR with knowledge and applications transferred to human anatomy, related research, and development subjects and to clinical settings. A series of 150 routine, clinical, pelvic CT protocols of European and Asian males and females (64 ± 15 (20-90) years old) were post-processed to compute gender- and ancestry-specific 3D statistical models of the pelvic ring. Evaluations comprised principal component analysis (PCA) that included size, shape, and asymmetry patterns and their variations to be assessed. Four different CT-based 3D statistical models of the entire pelvic ring were computed according to the gender and ancestry specific groups. PCA mainly displayed size and shape variations. Examination of additional PCA modes permitted six distinct asymmetry patterns to be identified. They were located at the sacrum, iliac crest, pelvic brim, pubic symphysis, inferior pubic ramus, and near to the acetabulum. Accordingly, the pelvic ring demonstrated not to be entirely symmetric. Assessment of its asymmetry proved to be a challenging task. Using CT-based 3D statistical modeling and PCA, we identified six distinct APRs that were located at different anatomical regions. These regions are more prone to APRs than other sites. Minor asymmetry patterns have to be distinguished from the distinct APRs. Side differences with regard to size, shape, and/or position require to be taken into account. APRs may be due different load mechanisms applied via spine or lower extremity or locally. There is a need for simpler and efficient, yet reliable methods to be routinely transferred to human anatomy, related research, and development subjects and to clinical settings.

Nailing vs. plating in comminuted proximal ulna fractures - a biomechanical analysis.

BACKGROUND: Comminuted proximal ulna fractures are severe injuries with a high degree of instability. These injuries require surgical treatment, usually angular stable plating or double plating is performed. Nailing of proximal ulna fracture is described but not performed regularly. The aim of this study was to compare a newly developed, locked proximal ulna nail with an angular stable plate in an unstable fracture of the proximal ulna. We hypothesize, that locked nailing of the proximal ulna will provide non-inferior stability compared to locked plating. METHODS: A defect fracture distal to the coronoid was simulated in 20 sawbones. After nailing or plate osteosynthesis the constructs were tested in a servo-pneumatic testing machine under physiological joint motion (0°-90°) and cyclic loading (30 N - 300 N). Intercyclic osteotomy gap motion and plastic deformation of the constructs were analyzed using micromotion video-analysis. RESULTS: The locked nail showed lower osteotomy gap motion (0.50 ± 0.15 mm) compared to the angular stable plate (1.57 ± 0.37 mm, p < 0.001). At the anterior cortex the plastic deformation of the constructs was significantly lower for the locked nail (0.09 ± 0.17 mm vs. 0.39 ± 0.27 mm, p = 0.003). No statistically significant differences were observed at the posterior cortex for both parameters. CONCLUSIONS: Nail osteosynthesis in comminuted proximal ulna fractures shows lower osteotomy gap motion and lower amount of plastic deformation compared to locking plate osteosynthesis under laboratory conditions.

Open reduction and internal fixation of acetabular fractures in patients of old age.

MATERIAL AND METHODS: There is an ongoing debate on which treatment for acetabular fractures in elderly patients is the most appropriate. This study was set up to identify the role of open reduction and internal fixation of acetabular fractures in persons of old age. We retrospectively reviewed the medical charts and radiological data of all patients older than 65 years, who suffered an isolated acetabular fracture and were admitted in our Department between 2010 and 2014 (5-year period). Complications, outcome and mortality were recorded. Of all surviving patients, quality of life (QoL), mobility and independence were graded with European Quality of Life 5 Dimensions 3 Level (EQ-5D-3L), European Quality of Life 5 Dimensions Visual Analogue Scale (EQ-5D-VAS), Numeric Rating Scale (NRS), Elderly Mobility Scale (EMS) and Tinetti Mobility Test (TMT). RESULTS: Seventy patients could be identified. There were 52 men (74%) and 18 women (26%) with a median age of 79.0 years (range: 65-104 years). Forty-six patients (66%) had been treated with open reduction and internal fixation (ORIF), 24 (34%) conservatively. There were negative predictive factors-subchondral impaction, damage to the femoral head and multiple fragments-in 54% of the operative group. With ORIF, an anatomical reduction could be achieved in 27 patients (59%), an acceptable in 18 (39%) and a poor in one (2%). At follow-up, 18 patients (26%) had died and 23 (33%) were not able to participate. The follow-up rate of the surviving operatively treated patients was 77%. Eleven of 46 operated patients (24%) needed a conversion to a total hip arthroplasty (THA). All patients undergoing conversion had imperfect reduction after surgery. No patient in the non-operative group underwent conversion to THA during follow-up. The median follow-up time of operatively treated patients without conversion (n = 17) was 30 months (range, 16-73 months), of patients with THA (n = 9) 30 months after conversion (range, 17-55 months). Quality of reduction correlated to QoL, mobility and independence in all recorded parameters. Patients with secondary THA had similar good outcomes as patients after ORIF without later conversion. Men had better outcome than women. CONCLUSION: ORIF of acetabular fractures in patients of old age results in excellent outcomes at short-term follow-up when anatomical reduction can be achieved. In case of negative predictive factors, ORIF cannot be regarded as a definitive solution, rather as the construction of a stable socket for secondary THA. The decision of therapy should be made dependent on pre-operative radiographic parameters.

3D statistical model of the pelvic ring - a CT-based statistical evaluation of anatomical variation.

The pelvic ring is a highly complex construct with a central role for human stability and mobility. The observable interindividual differences in skeletal anatomy are caused by anatomical variation in the innominate bones as well as the sacrum, further to differences in the spatial arrangement of these bones to each other. The aim of this study was to generate a 3D statistical model of the entire pelvic ring in order to analyse the observed interindividual differences and anatomical variation. A series of 50 anonymized pelvic CT scans of uninjured Japanese adults [30 males, 20 females, average age of 74.9 years, standard deviation (SD) 16.9 years] were processed and analysed, resulting in a 3D statistical overall mean model and separate male and female mean models. Principal component analysis (PCA) of the overall statistical model predominantly showed size variation (20.39%) followed by shape variation (14.13%), and a variation of the spatial arrangement of the sacrum to the innominate bones in different anatomical peculiarities (11.39 and 8.85%). In addition, selected internal and external pelvic parameters were manually measured with the objective of further evaluating and quantifying the observed interindividual as well as the known sex-specific differences. A separate statistical model of the grey value distribution based on the given Hounsfield unit (HU) values was calculated for assessing bone mass distribution, thus an indication of bone quality utilizing grey values as a quantitative description of radiodensity was obtained. A consistent pattern of grey value distribution was shown, with the highest grey values observed between the sacro-iliac joint and the acetabulum along the pelvic brim. Low values were present in the sacral ala, in the area of the iliac fossa as well as in the pubic rami next to the symphysis. The present model allows a differentiated analysis of the observed interindividual variation of the pelvic ring and an evaluation of the grey value distribution therein. Besides providing a better understanding of anatomical variation, this model could be also used as a helpful tool for educational purposes, preoperative planning and implant design.

[Fragility fractures of the pelvis]. / Fragilitätsfrakturen des Beckens.

Fragility fractures of the pelvis are increasing in frequency. In most cases patients suffer a minor injury, have intense pain in the pelvic region and impaired mobility. The new fragility fractures of the pelvis (FFP) classification distinguishes between four types with increasing instability. The FFP types I and II are treated conservatively. For FFP types III and IV and type II with unsuccessful conservative treatment, minimally invasive stabilizing techniques are recommended. Both the posterior and anterior pelvic ring must be stabilized. Alternative techniques for dorsal stabilization are iliosacral screw and transsacral bar osteosynthesis, transiliac internal fixator and lumbopelvic fixation. External fixation, retrograde transpubic screw fixation, anterior internal fixation and plate and screw osteosynthesis are alternatives for the anterior pelvic ring. Treatment of fragility fractures of the pelvis should be carried out as part of an orthogeriatric co-management.

Is the novel olecranon tension plate a valid alternative to tension band wiring of olecranon fractures? A biomechanical study on cadaver bones.

INTRODUCTION: Tension band wiring (TBW) used for olecranon fractures is afflicted with a high rate of complications. The aim of this study was to compare the stability of the TBW versus an alternative, novel low-profile olecranon tension plate (OTP) with angular stable screws in a simulated complex fracture model. MATERIALS AND METHODS: Nine fresh-frozen pairs of cadaver proximal ulnae with an oblique osteotomy and an additional wedge fragment simulating an unstable fracture were tested. The TBW and OTP were implanted pairwise. The elbow motion was simulated in a single-muscle model and ranged from full extension to 90° of flexion. The pulling force of the triceps tendon ranged from 50 to 200 N. The displacement of the fracture fragments was measured with a video motion analysis system over 304 cycles. Data were assessed statistically using the Wilcoxon signed-rank test. RESULTS: The cyclic loading tests showed mean loosening of the fracture fragments at the articular surface of 0.56 mm using TBW (SD 0.65) and 0.15 mm for OTP (SD 0.39). There was no statistical significance in loosening between the two constructs (p = 0.31). No plate breakage or screw loosening occurred. CONCLUSIONS: The low-profile OTP, using the principles of pre-tensioning, lag, cortical, and angular stable screws together, demonstrated similar stability after olecranon fracture fixation when compared with the TBW technique and a lag screw in the olecranon fracture model with a third wedge fragment.

Olecranon tension plating or olecranon tension band wiring? A comparative biomechanical study.

PURPOSE: The complication rate of a tension band wiring (TBW) used for the internal fixation of olecranon fractures remains high. The aim of this study was to compare the stability of a novel olecranon tension plate (OTP) with TBW in a simulated fracture model. METHODS: We tested 12 fresh frozen-pairs of cadaver proximal ulnae treated with OTP and TBW under cyclic loading. The elbow motion ranged from full extension to 90° of flexion, and the pulling force of the triceps tendon ranged from 50 to 350 N. The displacement of the fracture fragments was measured continuously. Data were assessed statistically using the Wilcoxon test with significance level of p < 0.05. RESULTS: The cyclic loading tests showed median displacements of the fracture fragments of 0.25 mm using OTP and 1.12 mm for TBW. Statistical analysis showed the difference to be substantial (p = 0.086) but not statistically significant. No plate breakage or screw loosening occurred. CONCLUSIONS: The concept of replacing prominent K-wires at the proximal end of the ulna using an low-profile plate with classical lag and multidirectional angle-stable screws demonstrated biomechanical advantages over TBW.

[Disproportionately increased incidence of proximal femoral fractures in a level one trauma center : Epidemiological analysis from 2016 to 2022]. / Überproportional angestiegene Inzidenz proximaler Femurfrakturen in einem Level-One-Traumazentrum : Epidemiologische Analyse von 2016 bis 2022.

BACKGROUND: Proximal femoral fractures represent the most frequent fracture entity in Germany accounting for more than 20% of all fractures. According to a decision of the Federal Joint Committee from 2019, proximal femoral fractures also have to be surgically treated within 24 h. In order to quantify a subjectively perceived increase in workload in trauma surgery at a supraregional trauma center, a retrospective analysis of the number of surgically treated proximal femoral fractures was performed. Proximal femoral fractures were chosen due to their high incidence and homogeneous treatment. METHODS: Using ICD-10 codes, all surgically treated proximal femoral fractures from 2016 to 2022, including the patient's zip code, were retrieved from the database of the trauma center. RESULTS: The number of surgically treated proximal femoral fractures doubled from 2016 to 2022. The highest increase (60%) was recorded from 2020 to 2022. Heat maps show an increase in the catchment area radius as well. CONCLUSION: When compared (inter)nationally, a disproportionate increase in the amount of surgically treated proximal femoral fractures was recorded at the trauma center studied. The increase of the catchment area radius and the number of patients treated in the urban area show that less and less hospitals participate in emergency treatment. Possible explanations are a lack of resources aggravated by the recent COVID-19 pandemic and a lack of qualified personnel, interface problems between the federal states or the strict requirements of the Federal Joint Committee in the treatment of proximal femoral fractures. It must be assumed that there is a clearly increased workload for all professions involved in the trauma center investigated, although the infrastructure has remained unchanged.

Functional outcomes after intramedullary nailing (C-Nail®) of severe calcaneal fractures with mean follow-up of 36 months.

PURPOSE: Calcaneal fractures (CFs) are rare but potentially debilitating injuries. Apart from the open, far lateral or sinus tarsi approach, operative treatment can be performed minimally invasive and percutaneously with intramedullary nailing. In this study, we sought to investigate the functional outcome of severe CFs treated with the C-Nail® implant. METHODS: Twenty-two CFs (9 × Sanders III and 8 × Sanders IV), operated between 2016 and 2019, were followed up with a mean duration of 36 (± 11) months. The AOFAS score, pre- and postoperative Böhler angles, wound healing disorders, and patient-reported outcome measures (PROMs) like pain levels and return to work/sport levels were assessed. RESULTS: The mean AOFAS score was 72.0 (± 9.8). Four patients sustained wound healing disorders, yet no implant-associated surgical revision was required. Fifty percent of patients were pain-free within 1 year. Within 1 year, about 50% of the patients could return to sports, and about 80% of the patients could return to work. PROMs and functional results align with those from other implants reported in the literature. CONCLUSION: Intramedullary nailing of severe CFs with the C-Nail® implant can be considered a safe treatment alternative that yields acceptable results at mid-terms.

Do we need to fix the anterior fracture component in insufficiency fractures of the pelvis? A biomechanical comparison on an FFP type IIIc fracture in an osteoporotic pelvic bone model.

There is a growing understanding of the specific characteristics of insufficiency fractures of the pelvis and of general requirements for the treatment of affected patients with focus on early mobilization and effective pain reduction as the main goals of therapy. While there is consensus on the significance of achieving stability of the dorsal pelvic ring structures there is still an open discussion about the potential benefits of additional stabilization of an anterior fracture component. Within a biomechanical test setup, two established methods of dorsal fracture fixation were tested under axial loading (25-1200 N; 1000 test cycles) on an explicit osteoporotic bone model (n = 32) with a standardized FFP type IIIc fracture with and without additional fixation of the anterior fracture component. Dorsal fixation was performed with and long and a short 7.3 mm cannulated screw in S1 in one group (n = 16), and a trans sacral bar with an additional short 7.3 mm cannulated screw in S1 in the other group (n = 16). Half of the samples received a 7.3 mm cannulated retrograde transpubic screw for anterior fixation. The fixation with the trans sacral bar and the additional anterior screw fixation showed the highest rate of stability (p = 0.0014), followed by the double SI-screw fixation with stabilization of the anterior fracture (p = 0.0002). During testing, we observed the occurrence of new sacral fractures contralateral to the initial fracture in 22/32 samples. The results let us assume that stabilization of an additional anterior fracture component relevantly improves the stability of the entire ring construct and might prevent failure of the dorsal stabilization or further fracture progression.

Prospective assessment of key factors influencing treatment strategy and outcome of fragility fractures of the pelvis (FFP).

BACKGROUND: Fragility fractures of the pelvis (FFP) are a clinical entity with an increasing significance in clinical practice. Little is known about the conditions, which influence decision making and outcome. SETTING: Level I trauma center. MATERIAL AND METHODS: Prospective assessment of selected parameters of patients, who were admitted with a FFP in a 2-year period. Fractures were classified in accordance with the Rommens and Hofmann classification. Living environment, level of autonomy (independent walking), type of treatment (conservative versus operative), type of surgical technique, European Quality of Life-5 Dimensions-5 Levels (EQ-5D-5L), Short Form-8 Physical Component Score (SF-8 PCS) and Short Form-8 Mental Component Score (SF-8 MCS), Barthel Index, Parker Mobility Score (PMS) and Numeric Rating Scale (NRS) were collected at primary presentation (t1), at discharge (t2) and after 3 (t3) and 12 months (t4). Length of hospital stay, in-hospital complications, surgery-related complications, new osteoporotic fractures and mortality rate within the first year were also registered. The key factors influencing the choice of therapy and outcome were looked for. RESULTS: 110 patients, 99 women (90%) and 11 men (10%), were included in the study. Their mean age was 79.2 years (SD 10 years). Fourteen patients had FFP type I (12.7%), 59 FFP type II (53.6%), 11 FFP type III (10%) and 26 FFP type IV fractures (23.6%). All patients with FFP type I were treated conservatively. 48 patients with FFP types II-IV were treated conservatively and 48 operatively. Patients, who got a conservative outpatient treatment first and were hospitalized later, had higher FFP fracture types at admission. Operatively treated patients were hospitalized at a median of 33.5 days after the beginning of complaints, whereas the median day of admission of the conservative group was the day of trauma (p < 0.001). The operatively treated patients were hospitalized in a worse clinical condition (SF-8 PCS, EQ-5D-5L, autonomy). Length of stay (LoS) of operatively treated patients was significantly longer than of conservatively treated (p < 0.001). There was a tendency to more in-hospital complications in the operative group (p = 0.059). The rate of surgery-related complications (8.3%) was low with only one revision needed. Selected outcome parameters improved during the observation period nearly reaching the level before FFP after 1 year. SF-8 PCS, Barthel index and rate of patients living home were higher in the operative group at t4. The improvement of autonomy (independent walking) between t1 and t4 was significant in the operated group (p = 0.04) but not in the conservative group (p = 0.96). One-year mortality rate was 11.7% with no difference between the fracture types. One-year mortality rate of conservatively treated patients with FFP type II-IV was 13.5% versus 6.9% in the operative group (p = 0.38). CONCLUSION: Conservative treatment is appropriate in patients with FFP type I as well as in patients with FFP type II, provided that the last ones are hospitalized immediately after the traumatic event. Surgical treatment is recommended in patients with higher fracture types, with delayed presentation or after unsuccessful conservative treatment. In the conservative and operative group, all selected parameters considerably improved between t1 and t4 with a steeper increase in the operative group. The rate of postoperative complications is low. The 1-year mortality rate is the lowest in the operative group. Surgical stabilization of FFP is safe and reliable provided it is performed with care and in the appropriate target group.

[Minimally invasive stabilization of fragility fractures of the pelvis with transsacral bar and retrograde transpubic screw]. / Minimal-invasive Stabilisierung von Fragilitätsfrakturen des Beckens mittels transsakralem Stab und retrograder transpubischer Schraube.

OBJECTIVE: Stabilization of fragility fractures of the pelvis (FFP) using a minimally invasive technique. Insertion of a transsacral rod into the transsacral corridor of S1. Insertion of a retrograde transpubic screw through the superior branch of the pubic bone. INDICATIONS: Uni- or bilateral displaced fragility fractures of the sacrum or sacroiliac joint. Nondisplaced fractures of the sacrum or sacroiliac joint in case of nonsuccessful conservative treatment. Uni- or bilateral fractures of the superior branch of the pubic bone, which are present in combination with a posterior pelvic instability. CONTRAINDICATIONS: Fragility fractures of the pelvis, which can be successfully treated conservatively. Absence of transsacral corridor in sacral body S1. Major displacement, nonreducible fractures of the superior branch of the pubic bone. Soft tissue infection at insertion site of implants. SURGICAL TECHNIQUE: The transsacral bar is inserted under fluoroscopic control from ilium to ilium through the transsacral corridor of the sacral body S1. The retrograde transpubic screw is inserted from the pubic tubercle through the superior branch of the pubic bone past the acetabulum into the body of the ilium. POSTOPERATIVE MANAGEMENT: An early mobilization with weight bearing of both lower extremities as tolerated by the patient is allowed. Conventional radiographs for control of the position of the implants and fractures are taken after mobilization RESULTS: In all, 64 patients with FFP type II, FFP type III or FFP type IV were stabilized with a transacral bar osteosynthesis in the posterior pelvis. In 32 patients (50%), additional sacroiliac screws were inserted. In 29 patients (45.3%) the transsacral bar osteosynthesis was combined with a transpubic retrograde screw. Median length of hospital stay was 17.5 days. In all, 20 patients (31.3%) suffered general, 10 patients (15.6%) suffered surgery-related complications, and 41 patients (64.1%) were mobile in the room or on the ward at discharge. One-year mortality was 10.9%. The values of the SF­8 Physical and Mental Component Scores, Parker Mobility Score and Numeric Rating Scale were moderate, yet comparable with the values of patients of the same age.

Pleiotropic Long-Term Effects of Atorvastatin on Posttraumatic Joint Contracture in a Rat Model.

The antifibrotic effect of atorvastatin has already been demonstrated in several organ systems. In the present study, a rat model was used to investigate the effect of atorvastatin on posttraumatic joint contracture. Forty-eight Sprague Dawley rats were equally randomized into an atorvastatin group and a control group. After initial joint trauma, knee joints were immobilized for intervals of 2 weeks (n = 16) or 4 weeks (n = 16) or immobilized for 4 weeks with subsequent remobilization for another 4 weeks (n = 16). Starting from the day of surgery, animals received either atorvastatin or placebo daily. After euthanasia at week 2, 4 or 8, joint contracture was determined, histological examinations were performed, and gene expression was assessed. The results suggest that the joint contracture was primarily arthrogenic. Atorvastatin failed to significantly affect contracture formation and showed a reduction in myofibroblast numbers to 98 ± 58 (control: 319 ± 113, p < 0.01) and a reduction in joint capsule collagen to 60 ± 8% (control: 73 ± 9%, p < 0.05) at week 2. Gene expression of α-smooth muscle actin (α-SMA), collagen type I, transforming growth factor ß1 (TGF-ß1) and interleukin-6 (IL-6) was not significantly affected by atorvastatin. Atorvastatin decreases myofibroblast number and collagen deposition but does not result in an improvement in joint mobility.

Nailing of proximal ulna fractures: biomechanical comparison of a new locked nail with angular stable plating.

PURPOSE: Proximal ulna fractures are common injuries and frequently treated with angular stable plating. This surgical option shows good functional results. Relevant drawbacks such as large soft tissue exposure, compromised blood supply of fracture fragments and disturbing osteosynthetic material are described. The aim of this study was to compare a new locked proximal ulna nail with angular stable plating in a biomechanical testing setup for extraarticular proximal ulna fractures. METHODS: Ten pairs of sawbones with a Jupiter type IIB proximal ulna fracture (OTA 2U1A3.1) were tested after osteosynthesis with the mentioned implants in a servo-pneumatic testing machine. The testing setup simulates physiological joint motion (0°-90°) under cyclic loading (30-300 N). Primary stability and loosening of both constructs were quantified using micromotion video-analysis after 608 test cycles. RESULTS: The micromotion analysis showed significantly higher primary stability of the locked nail (0.29 ± 0.13 mm) compared to the angular stable plate (0.97 ± 0.30 mm, p < 0.001). Both implants showed a low amount of loosening after completion of the test cycles. The construct with the locked nail (0.08 ± 0.06 mm) showed significantly lower dislocation of the fragments measured at the anterior cortex (plate 0.24 ± 0.13 mm, p < 0.001). CONCLUSION: Nailing of proximal ulna fractures shows significantly higher primary stability and lower loosening compared to angular stable plating in our testing setup.

Artificial intelligence and CT-based 3D statistical modeling to assess transsacral corridors and plan implant positioning.

Transsacral corridors at levels S1 and S2 represent complex osseous spaces allowing percutaneous fixation of non- or minimally-displaced fragility fractures of the sacrum. To safely place transsacral implants, they must be completely intraosseous. However, standard radiographs and CT do not properly demonstrate the corridor's intricate configuration. Our goal was to facilitate the three-dimensional assessment of transsacral corridors using artificial intelligence and the planning of transsacral implant positioning. In total, 100 pelvic CTs (49 women, mean age: 58.6 ± SD 14.8 years; 51 men, mean age: 60.7 ± SD 13 years) were used to compute a 3D statistical model of the pelvic ring. On the basis of morphologic features (=predictors) and principal components scores (=response), regression learners were interactively trained, validated, and tuned to predict/sample personalized 3D pelvic models. They were matched via thin-plate spline transformation to a series of 20 pelvic CTs with fragility fractures of the sacrum (18 women and 2 men, age: 69-9.5 years, mean age: 78.65 ± SD 8.4 years). These models demonstrated the availability, dimension, cross-section, and symmetry of transsacral corridors S1 and S2, as well as the planned implant position, dimension, axes, and entry and exit points. The complete intraosseous pathway was controlled in CT reconstructions. We succeeded to establish a workflow determining transsacral corridors S1 and S2 using artificial intelligence and 3D statistical modeling.

Anatomical evaluation of the transpubic screw corridor based on a 3D statistical model of the pelvic ring.

Retrograde transpubic screw fixation is a common procedure for the treatment of anterior pelvic ring fractures. With its sparing surgical approach and significant pain relief after screw fixations allowing early mobilisation, it has gained importance especially in the treatment of insufficiency fractures in elderly patients. However, positioning of transpubic screw osteosynthesis is not always possible due to narrowness and curvature of the screw corridor. The aim of the present study was to evaluate availability and length of the screw corridor using a 3D statistical model of the pelvic ring consisting out of 150 uninjured pelves. Virtual bore probes with a diameter of 7.5 mm were analysed as to accessibility, length and grey value distribution in Hounsfield Unit (HU). A transpubic corridor with a diameter of ≥ 7.5 mm was available in 185 of 300 investigated superior pubic rami with mean screw length of 131.7 mm. Accessibility of the screw corridor was higher in males than in females. However, screw length showed no systematic differences between the sexes or ethnicities. Analysis of the grey value distribution demonstrated the strongest bone to be located at the lateral ilium and the supraacetabular region.

Minimal-invasive stabilization of anterior pelvic ring fractures with retrograde transpubic screws.

BACKGROUND: In the vast majority of patients with pelvic ring lesions, there is a combination of fractures of the posterior and anterior pelvic ring. Anterior fractures are painful and contribute to loss of stability of the pelvic ring. For these reasons, stabilization of pubic rami fractures is recommended together with posterior pelvic ring fixation. Retrograde transpubic screw osteosynthesis enjoys increasing acceptance due to its minimal invasive technique and adequate stability. PATIENTS AND METHODS: We retrospectively reviewed the results of 158 retrograde transpubic screw osteosyntheses in 128 patients with pelvic ring lesions including a pubic ramus fracture. Sixty-three patients suffered a high-energy injury, 65 a fragility fracture of the pelvis. RESULTS: One hundred and forty-six screws (92.4%) were inserted through a percutaneous procedure. There were no vascular, neurological or urological complications. Fifty-nine screws (39%) yielded an excellent reduction with less than one cortical width of displacement. Slight secondary displacement was seen in 33 of these fractures (55.9%). Early surgical complications were seen in 16 screws (10.1%): suboptimal pathway in 10, local hematoma in 4 and local infection in 3. Early revision surgery was done in 7 screws (4.4%). Median follow-up was 27.6 weeks, 83 screws (52.5%) had a follow-up of more than 6 months. During follow-up, 7.6% of screws loosened. Operative revision was performed in 13%. 75 fractures (90.3%) with a follow-up of ≥ 6 months showed radiographic evidence of healing. There was no difference in the healing rate of high-energy and fragility fractures. Nonunion rate was not dependent on the quality of primary reduction, secondary displacement, or screw loosening. Infection (p 0.001) and surgery ≥ 6 months after trauma (p 0.02) more often led to nonunion. CONCLUSION: Retrograde transpubic screw osteosynthesis is a reliable method for splinting pubic rami fractures in high and low energy pelvic trauma. Although a slight secondary fracture displacement is seen in most cases, it does not affect fracture healing. Retrograde transpubic screw is a adequate minimal-invasive osteosynthesis to stabilize the anterior pelvic ring, especially in fragility fracture of the pelvis. Delayed operation (> 6 months) and infection show higher rate of nonunion.

When and How to Operate Fragility Fractures of the Pelvis?

Fragility fractures of the pelvis (FFP) are an entity with an increasing frequency. The characteristics of these fractures are different from pelvic ring fractures in younger adults. There is a low energy instead of a high energy trauma mechanism. Due to a specific and consistent decrease of bone mineral density, typical fractures in the anterior and posterior pelvic ring occur. Bilateral sacral ala fractures are frequent. A new classification system distinguishes between four categories with increasing loss of stability. The subtypes represent different localizations of fractures. The primary goal of treatment is restoring mobility and independency. Depending on the amount of instability, conservative or surgical treatment is recommended. The operative technique should be as less invasive as possible. When the broken posterior pelvic ring is fixed operatively, a surgical fixation of the anterior pelvic ring should be considered as well. FFP Type I can be treated conservatively. In many cases, FFP Type II can also be treated conservatively. When conservative treatment fails, percutaneous fixation is performed. FFP Type III and FFP Type IV are treated operatively. The choice of the operation technique is depending on the localization of the fracture. Iliosacral screw osteosynthesis, transsacral bar osteosynthesis, transiliac internal fixation, and iliolumbar fixation are alternatives for stabilization of the posterior pelvic ring. Plate osteosynthesis, retrograde transpubic screw, and anterior internal fixation are alternatives for stabilization of the anterior pelvic ring. Postoperatively, early mobilization, with weight bearing as tolerated, is started. Simultaneously, bone metabolism is also analyzed and its defects compensated. Medical comorbidities should be identified and treated with the help of a multidisciplinary team.

Treatment of distal intraarticular tibial fractures: A biomechanical evaluation of intramedullary nailing vs. angle-stable plate osteosynthesis.

In factures of the distal tibia with simple articular extension, the optimal surgical treatment remains debatable. In clinical practice, minimally invasive plate osteosynthesis and intramedullary nailing are both routinely performed. Comparative biomechanical studies of different types of osteosynthesis of intraarticular distal tibial fractures are missing due to the lack of an established model. The goal of this study was first to establish a biomechanical model and second to investigate, which are the biomechanical advantages of angle-stable plate osteosynthesis and intramedullary nailing of distal intraarticular tibial fractures. Seven 4(th) generation biomechanical composite tibiae featuring an AO 43-C2 type fracture were implanted with either osteosynthesis technique. After primary lag screw fixation, 4-hole Medial Distal Tibial Plate (MDTP) with triple proximal and quadruple distal screws or intramedullary nailing with double proximal and triple 4.0mm distal interlocking were implanted. The stiffness of the implant-bone constructs and interfragmentary movement were measured under non-destructive axial compression (350 and 600 N) and torsion (1.5 and 3Nm). Destructive axial compression testing was conducted with a maximal load of up to 1,200 N. No overall superior biomechanical results can be proclaimed for either implant type. Intramedullary nailing displays statistically superior results for axial loading in comparison to the MDTP. Torsional loading resulted in non-statistically significant differences for the two-implant types with higher stability in the MDTP group. From a biomechanical view, the load sharing intramedullary nail might be more forgiving and allow for earlier weight bearing in patients with limited compliance.