How exactly can computer simulation predict the kinematics and contact status after TKA? Examination in individualized models

BackgroundIt is unknown whether a computer simulation with simple models can estimate individual in vivo knee kinematics, although some complex models have predicted the knee kinematics. The purposes of this study are first, to validate the accuracy of the computer simulation with our developed model during a squatting activity in a weight-bearing deep knee bend and then, to analyze the contact area and the contact stress of the tri-condylar implants for individual patients.MethodsWe compared the anteroposterior (AP) contact positions of medial and lateral condyles calculated by the computer simulation program with the positions measured from the fluoroscopic analysis for three implanted knees. Then the contact area and the stress including the third condyle were calculated individually using finite element (FE) analysis.FindingsThe motion patterns were similar in the simulation program and the fluoroscopic surveillance. Our developed model could nearly estimate the individual in vivo knee kinematics. The mean and maximum differences of the AP contact positions were 1.0 mm and 2.5 mm, respectively. At 120° of knee flexion, the contact area at the third condyle was wider than the both condyles. The mean maximum contact stress at the third condyle was lower than the both condyles at 90° and 120° of knee flexion.InterpretationIndividual bone models are required to estimate in vivo knee kinematics in our simple model. The tri-condylar implant seems to be safe for deep flexion activities due to the wide contact area and low contact stress.     

Biopsies of pediatric brainstem lesions display low morbidity but strong impact on further treatment decisions

ObjectiveThe course of malignant brain stem gliomas in childhood is rarely positive. Because of limited therapeutic options and potentially hazardous biopsies oncologist often relay on MRI diagnoses only for further therapy decisions. In this study we show that brain stem biopsies display a low morbidity rate and neuropathological assessment has a considerable impact on further treatment decision.MethodsWithin 18-months five children with brainstem symptoms and the radiological diagnosis of a malignant brainstem glioma, were identified. From this time point it was possible to analyze all samples with the 450 K methylome analysis. Other neuropathological techniques included classical histology with immunohistochemistry. Surgery was performed as biopsy, either microsurgical, frame-guided (Leksell), robot-assisted (ROSA) or navigated (BrainLab, two children).ResultsMean age of the children was 7.5 years (range: newborn to 12 years). There was no biopsy-related morbidity or mortality. The mean number of taken samples was 12 (range: 1–25). Histologic diagnosis could be established in all children, however, 450 K methylome diagnosis was positive in only two out of five patients.ConclusionDespite the technically difficult biopsies, all specimens were sufficient for immunohistochemical diagnosis, however, 450 K methylome analysis could only be better established where multiple small samples were taken, instead of few larger ones. Based on the preoperative radiological diagnosis suggesting malignant brainstem glioma, all children would have been treated with combined radiation and temozolomid chemotherapy. Nevertheless, due to the availability of histology and molecular diagnostics, individualized therapy could be performed, preventing in two out of five children from unnecessary radiation and chemotherapy.     

Complications and operative spine fusion construct length in Parkinson’s disease: A nationwide population-based analysis

There remains a dearth of information regarding the surgical complications following multilevel spine surgery in Parkinson’s disease (PD) patients. This retrospective cohort study was performed to address this issue on a nationwide level using the Nationwide Inpatient Sample from 2001 to 2012. More than 25 postoperative variables were analyzed to assess the impact of fusion construct length on each variable. Subsequently, the same analysis was performed on admissions without PD. 4301 PD patients with spine fusion were identified, of whom 934 (21.7%) underwent fusion of at least three levels; the remaining 3367 underwent fusion of 1–2 levels. Patients with 3+ level fusions were more likely to suffer paraplegia (P = .001; OR = 3.0; 95%CI = 1.5–6.1), hematoma/seroma (P = .009; OR = 1.9; 95%CI = 1.2–3.2), IVC filter placement (P = .018; OR = 2.1; 95%CI = 1.1–3.9), RBC transfusion (P < .001; OR = 3.2; 95%CI = 2.7–3.8), PE (P = .027; OR = 4.5; 95%CI = 1.2–16.9), postoperative shock (P = .023; OR = 7.3; 95%CI = 1.3–39.6), ARDS (P < .001; OR = 4.1; 95%CI = 2.7–6.3), VTE (P = .006; OR = 2.6; 95%CI = 1.3–5.4), acute posthemorrhagic anemia (P < .001; OR = 2.0; 95%CI = 1.7–2.4), device-related complications (P < .001; OR = 3.1; 95%CI = 2.3–4.2), and in-hospital mortality (P = .005; OR = 3.4; 95%CI = 1.5–7.4). 3+ level fusions were also more likely to have LOS > 1 week (P < .001; OR = 2.1; 95%CI = 1.8–2.5), and a nonroutine discharge (P = .005; OR = 1.9; 95%CI = 1.4–2.4). 692,173 non-PD patients with spine fusion were identified; 123,964 (17.9%) underwent 3+ level fusion. Differences between 3+ versus 1–2 level fusions were similar to those in PD patient, but unlike PD patients, postoperative infection was significant while in-hospital mortality, PE and VTE were not. Fusion of at least three levels increased morbidity, mortality, and adverse discharge disposition compared with 1–2 level fusions. Nearly 80% of all spine fusions performed in the United States are fewer than three levels. These findings are worth considering during operative decision-making in both PD and non-PD patients.     

The 100 most influential publications pertaining to intracranial aneurysms and aneurysmal subarachnoid hemorrhage

The study of intracranial aneurysms has grown at an astounding rate since Sir Charles Symond’s association of hemorrhage within the subarachnoid space to intracranial aneurysms in 1923. These associations led to the first surgical treatment of an intracranial aneurysm with wrapping by Norman Dott in 1931, and shortly thereafter, clip ligation by Walter Dandy in 1938. Surgical outcomes were improved by the introduction of the operative microscope in the 1960s and perioperative care utilizing induced hypertension, hypovolemia, and hemodilution (“HHH therapy”). Recent monumental advancements, such as coil embolization in 1990 by Guglielmi, have continued to advance the field forward. The authors hope to highlight some of the most seminal and influential works. Herein, we utilize the technique of citation analysis to assemble a list of the 100 most influential works pertaining to aneurysmal subarachnoid hemorrhage published between the years 1900 and 2015 to honor these individuals and to provide guidance to current and future researchers in the field. We additionally calculate the effects of author, journal, topic, and study design on the overall influence of publications in this field.