Purpose: Bipolar hemiarthroplasty has been shown to have a lower rate of dislocation than total hip arthroplasty. However, as the influencing risk factors for bipolar hemiarthroplasty dislocation remain unclear, we aimed to analyse patient and surgeon-specific influencing risk factors for bipolar hemiarthroplasty dislocation. Methods: We retrospectively analysed patients who were operated between 2012 and 2018 and had dislocated bipolar hemiarthroplasty and matched them to patients without a dislocated bipolar hemiarthroplasty, operated between 2018 and 2019. The study was limited to patients who received either a pre- or postoperative pelvic computed tomography. Besides demographic, morphologic, and physiologic data, we analysed duration of surgery; ASA score; Charlson Comorbidity Index; Almelo Hip Fracture Score; Parker Score; and acetabular morphology angles including acetabular anteversion angle, posterior acetabular sector angle, posterior wall angle, and acetabular roofing. Results: We included nine patients with a dislocated bipolar hemiarthroplasty and 30 with a non-dislocated bipolar hemiarthroplasty. Patient-specific factors prompting a higher risk for dislocated bipolar hemiarthroplasty were longer duration of surgery (min) (115 ± 50 vs. 80 ± 27, p = 0.01); dementia (56% vs. 13%, p < 0.01); smaller posterior acetabular sector angle (°) (96 ± 6 vs. 109 ± 10, p < 0.01); and smaller posterior wall angle (°) (67 ± 6 vs. 77 ± 10, p = 0.02). Conclusion: Dementia and insufficient posterior wall angle were associated with higher risk of dislocation in bipolar hemiarthroplasty

BACKGROUND: The rupture of syndesmotic ligaments is treated with a screw fixation as the gold standard. An alternative is the stabilization with a TightRope®. A couple of studies investigated the different clinical outcome and some even looked at the stability in the joint, but none of them examined the occurring pressure after fixation. OBJECTIVE: Is there a difference in pressure inside the distal tibiofibular joint between a screw fixation and a TightRope®? Does the contact area differ in these two treatment options? METHODS: This biomechanical study aimed to investigate the differences in fixation of the injured syndesmotic ligaments by using a fixation with one quadricortical screw versus singular TightRope® both implanted 1 cm above the joint. By using 12 adult lower leg cadaveric specimens and pressure recording sensor, we recorded the pressure across the distal tibiofibular joint. Additionally we measured the contact surface area across the joint. RESULTS: The mean of the pressure across the distal tibiofibular joint from the start of the insertion of the fixation device to the complete fixation was 0.05 Pascal for the TightRope® and 0.1 for the screw (P= 0.016). The mean of the maximum pressure across the joint (after completion of fixation and releasing the reduction clamp) was 1.750 mega Pascal with the screw fixation and 0.540 mega Pascal with TightRope® (P= 0.008). The mean of the measured contact area of the distal tibiofibular joint after fixation was 250 mm2 in the TightRope® group and of 355 mm2 in the screw fixation (P= 0.123). CONCLUSIONS: The screw fixation is stronger and provides a larger surface contact area, which leads us to the conclusion that it provides a better stability in the joint. While previous clinical studies did not show significant clinical difference between the two methods of fixation, the biomechanical construct varied. Long term clinical studies are required to establish whether this biomechanical distinction will contribute to various clinical outcomes.

Purpose: Smaller posterior acetabular walls have been shown to independently influence the risk for bipolar hip dislocation. We asked whether differences would also be observed in patients with traumatic posterior hip dislocation with and without posterior wall fractures. Methods: Between 2012 and 2020 we observed 67 traumatic posterior hip dislocations. Of these, 43 traumatic posterior hip dislocations in 41 patients met the inclusion criteria. Eighteen dislocations were excluded with an acetabular fracture other than posterior wall fracture and six dislocations had insufficient computed tomography (CT) data. The mean age was 41 ± 11 years, 32 males and nine females. We observed 26 traumatic hip dislocations with posterior wall fractures and 17 without. All patients underwent polytrauma CT scans and postoperative/postinterventional pelvic CT scans. On axial CT-scans, posterior wall determining angles were measured. Results: Patients with posterior wall fractures were not significantly older than patients without posterior wall fractures (42 ± 12 vs. 38 ± 10 years; p = 0.17). Patients without posterior wall fractures had significantly smaller posterior acetabular sector angles (84° ± 10°) than did patients with posterior wall fractures (105° ± 12°) (p < 0.01; OR 1.178). Likewise, the posterior wall angle was significantly smaller in patients without posterior wall fracture (62° ± 9°) than in those with posterior wall fractures (71° ± 8°) (p < 0.01; OR 1.141). Conclusion: Both posterior acetabular sector angle and posterior wall angle are independent factors determining the posterior wall fracture morphology in patients with traumatic posterior hip dislocation. Age and the observed trauma mechanism did not differentiate between traumatic posterior hip dislocations with and without posterior wall fractures.

Due to their immunomodulatory and regenerative capacity, human bone marrow-derived mesenchymal stem cells (hBMSCs) are promising in the treatment of patients suffering from polytrauma. However, few studies look at the effects of sera from polytraumatized patients on hBMSCs. The aim of this study was to explore changes in hBMSC properties in response to serum from polytrauma patients taken at different time points after the trauma incident. For this, sera from 84 patients with polytrauma (collected between 2010 and 2020 in our department) were used. In order to test the differential influence on hBMSC, sera from the 1^st (D1), 5^th (D5), and 10^th day (D10) after polytrauma were pooled, respectively. As a control, sera from three healthy donors (HS), matched with respect to age and gender to the polytrauma group, were collected. Furthermore, hBMSCs from four healthy donors were used in the experiments. The pooled sera of HS, D1, D5, and D10 were analyzed by multicytokine array for pro-/anti-inflammatory cytokines. Furthermore, the influence of the different sera on hBMSCs with respect to cell proliferation, colony forming unit-fibroblast (CFU-F) assay, cell viability, cytotoxicity, cell migration, and osteogenic and chondrogenic differentiation was analyzed. The results showed that D5 serum significantly reduced hBMSC cell proliferation capacity compared with HS and increased the proportion of dead cells compared with D1. However, the frequency of CFU-F was not reduced in polytrauma groups compared with HS, as well as the other parameters. The serological effect of polytrauma on hBMSCs was related to the time after trauma. It is disadvantageous to use BMSCs in polytraumatized patients at least until the fifth day after polytrauma as obvious cytological changes could be found at that time point. However, it is promising to use hBMSCs to treat polytrauma after five days, combined with the concept of Damage Control Orthopedics (DCO).

Background As part of the COVID-19 pandemic, political decisions were made to reduce social interaction and to reduce the number of infections. The aim was to create capacities for the in-hospital care of the patients. Objective The aim of the study was to check whether a reduction in the number of trauma patients compared to the mean of the previous 3 years could be observed. Material and methods We retrospectively analyzed all patients who presented in the emergency admission from 1 March to 15 April 2020 with the mean of the patients from the previous 3 years 2017-2019. The age of the patients, time of presentation, diagnoses, whereabouts of the patients, inpatient or outpatient, number and duration of the operative care and required capacity on the normal ward and intensive care units (ICU) were recorded. The injury mechanism was also examined. Results A total of 4967 patients between 1 March and 15 April were included. On average over the 3 previous years, a total of 1348 patients, i.e. 29.3 patients per day were counted in our emergency room. In 2020 a total of 923, i.e. 20 patients per day (p< 0.01) were counted. On average 227 (24.6%) were admitted to hospital compared to 311.5 (23.1%) in 2020. On average 143 operations were performed compared to 136 in 2020. The days on the ward were reduced from 2442 on average for the previous years, in 2020 to 1172 days by 52.1% (p< 0.01). The number of days on the ICU was 450 days on average in previous years and 303 days in 2020 (-32.7%,p< 0.01). Conclusion The number of patients in the emergency admission was significantly reduced in the observation period in 2020 compared to the mean of the previous 3 years. This directly made resources available for the care of COVID-19 patients.