The Impact of Anatomical Predisposition and Mechanism of Trauma on Dislocation of the Patella: A Retrospective Analysis of 104 Cases

Background: The aim of this study was to determine whether traumatic dislocation of the patella is provoked by the presence of predisposing factors and examine the role of the mechanism of injury. Methods: Cases diagnosed with dislocation of the patella and covered by the workers’ compensation program were identified and classified as traumatic based on insurance regulations. We examined predisposing factors (e.g., frontal axis, torsional deviation, trochlear dysplasia, patella alta) in case groups based on age at dislocation and trauma mechanism. Retrospective cohort study, level of evidence III. Results: Our sample size comprised 104 cases, consisting of 54 children and 50 adults. The most common mechanism of injury in children and adults was rotational trauma. Only 20% of the children and 21% of the adults exhibited no relevant predisposing factors. Group specifically, falls accounted for the highest number of cases exhibiting none of the defined anatomical predisposing factors. Children are more frequently affected by predisposition-related dislocations than adults. Conclusion: The proportion of predispositions is high. A fall, direct impact, or rotational trauma can be viewed as an adequate mechanism of trauma. For successful treatment, it is paramount to analyze the exact mechanism of the trauma and address any underlying predispositions

Patients’ expectations of osteotomies around the knee are high regarding activities of daily living

Purpose This study was conducted to investigate patients' expectations on high tibial osteotomies, distal femur osteotomies, and double-level osteotomies in different health-related domains. It was hypothesized that expectations are high in terms of capacity to work, pain relief, and restoring knee function. Methods A total of 264 patients (age 47 years +/- 11 years) were enrolled in this study from March 2015 until May 2016 in seven specialized orthopaedic surgery departments. Data were collected via the Knee injury and Osteoarthritis Outcome Score, the Hospital for Special Surgery-Knee Surgery Expectations Survey, and a ten-item (non-validated) questionnaire to specifically ask about expectations of osteotomies around the knee 24-48 h prior to surgery. In addition, self-efficacy was assessed. Parametric tests were used to test the hypothesis. Results Knee injury and Osteoarthritis Outcome Score test results showed that all patients suffered because of their knee impairments prior to surgery. All participants had high expectations in all aspects regarding the surgical outcome: on a four-point Likert scale ranging from 1 (very important) to 4 (not important), all mean values were between 1.2 and 1.7. For patients who had a demanding physical work, the ability to keep a stressful working posture was more important than for other patients (i.e. to kneel, to squat). Furthermore, preoperative lower quality of life was associated with higher expectations concerning improving the ability to walk, to achieve improvements in activities of daily living and social well-being. Conclusions Patients' expectations of osteotomies around the knee are high in terms of capacity to work, pain relief, and restoring functions. The natural course of osteoarthritis and the potential need for conversion to TKA were underestimated by a substantial proportion of the study population. However, the expectation regarding survival rate is in line with the reported literature. The results of this study should assist surgeons in discussing realistic expectations when considering and counselling patients regarding osteotomies around the knee. This may help to clarify realistic expectations preoperatively and ultimately improve patients' satisfaction

Interobserver reliability is higher for assessments with 3D software-generated models than with conventional MRI images in the classification of trochlear dysplasia

Purpose!#!Trochlear dysplasia is a significant risk factor for patellofemoral instability. The severity of trochlear dysplasia is commonly evaluated based on the Dejour classification in axial MRI slices. However, this often leads to heterogeneous assessments. A software to generate MRI-based 3D models of the knee was developed to ensure more standardized visualization of knee structures. The purpose of this study was to assess the intra- and interobserver agreements of 2D axial MRI slices and an MRI-based 3D software generated model in classification of trochlear dysplasia as described by Dejour.!##!Methods!#!Four investigators independently assessed 38 axial MRI scans for trochlear dysplasia. Analysis was made according to Dejour's 4 grade classification as well as differentiating between 2 grades: low-grade (types A + B) and high-grade trochlear dysplasia (types C + D). Assessments were repeated following a one-week interval. The inter- and intraobserver agreement was determined using Cohen's kappa (κ) and Fleiss kappa statistic (κ). In addition, the proportion of observed agreement (po) was calculated for assessment of intraobserver agreement.!##!Results!#!The assessment of the intraobserver reliability with regard to the Dejour-classification showed moderate agreement values both in the 2D (κ = 0.59 ± 0.08 SD) and in the 3D analysis (κ = 0.57 ± 0.08 SD). Considering the 2-grade classification, the 2D (κ = 0.62 ± 0.12 SD) and 3D analysis (κ = 0.61 ± 0.19 SD) each showed good intraobserver matches. The analysis of the interobserver reliability also showed moderate agreement values with differences in the subgroups (2D vs. 3D). The 2D evaluation showed correspondences of κ = 0.48 (Dejour) and κ = 0.46 (high / low). In the assessment based on the 3D models, correspondence values of κ = 0.53 (Dejour) and κ = 0.59 (high / low) were documented.!##!Conclusion!#!Overall, moderate-to-good agreement values were found in all groups. The analysis of the intraobserver reliability showed no relevant differences between 2 and 3D representation, but better agreement values were found in the 2-degree classification. In the analysis of interobserver reliability, better agreement values were found in the 3D compared to the 2D representation. The clinical relevance of this study lies in the superiority of the 3D representation in the assessment of trochlear dysplasia, which is relevant for future analytical procedures as well as surgical planning.!##!Level of evidence!#!Level II