Natural Corollaries Research Articles

High prevalence of associated injuries in anterior cruciate ligament tears: A detailed magnetic resonance imaging analysis of 254 patients

ObjectivesTo evaluate the type and prevalence of associated injuries by using magnetic resonance imaging (MRI) in patients with anterior cruciate ligament (ACL) tears.MethodsData from the Natural Corollaries and Recovery after ACL injury multicenter longitudinal cohort study were analyzed. Between May 2016 and October 2018, patients aged between 15 and 40 years, who had experienced an ACL tear within the last 6 weeks and sought medical attention at one of seven healthcare clinics in Sweden, were invited to participate. The mean time from injury to MRI was 19.6 ± 15.2 days. An orthopedic knee surgeon and a musculoskeletal radiologist reviewed all the MRI scans. The following structures were assessed: posterior cruciate ligament (PCL), medial collateral ligament (MCL) complex, lateral collateral ligament (LCL), popliteus tendon, medial meniscus (MM), lateral meniscus (LM), and cartilage. In addition, the presence of bone bruising, impaction fractures in the lateral femoral condyle (LFC) or posterolateral tibia (PLT), and Segond fractures were also assessed. ResultsA total of 254 patients (48.4% males) with a mean age of 25.4 ± 7.1 years were included. The prevalence of associated injuries was as follows: PCL (0.4%), MCL {41.3% [superficial MCL and deep MCL (dMCL) 16.5%; isolated dMCL 24.8%]}, LCL (2.4%), MM (57.4%), LM (25.2%), cartilage (15.0%), bone bruising (92.9%), impaction fracture in the LFC (45.7%) and PLT (4.7%), and Segond fracture (7.5%).ConclusionsThe prevalence of associated injuries in patients with ACL tears was high. The findings reported in this study may serve as a reference tool for orthopedic surgeons and radiologists in the diagnosis of associated injuries using MRI in patients with ACL tears.

High Prevalence of Superficial and Deep Medial Collateral Ligament Injuries on Magnetic Resonance Imaging in Patients With Anterior Cruciate Ligament Tears

To assess the prevalence of and factors associated with medial collateral ligament (MCL) complex injuries on magnetic resonance imaging (MRI) in patients with anterior cruciate ligament (ACL) tears. Data were extracted from the Natural Corollaries and Recovery After ACL Injury (NACOX) multicenter longitudinal cohort study. Between May 2016 and October 2018, patients who presented to 1 of 7 health care clinics across Sweden with an ACL tear sustained no more than 6 weeks earlier and who were aged between 15 and 40 years at the time of injury were invited to participate. All the patients included in this study underwent MRI. The mean time from injury to MRI was 19.6 ± 15.2 days. An orthopaedic surgeon specializing in knee surgery and a musculoskeletal radiologist reviewed all MRI scans. Injuries to the superficial MCL (sMCL), deep MCL (dMCL), and posterior oblique ligament were identified. Stepwise forward multiple binary logistic regression analyses were used to evaluate patient characteristics (age, sex, body mass index, preinjury Tegner activity level, and activity at injury) and injuries on MRI (lateral meniscus [LM] injury, medial meniscus [MM] injury, pivot shift-type bone bruising, medial femoral condyle [MFC] bone bruising, and lateral femoral condyle [LFC] impaction) associated with the presence of MCL complex tears. In total, 254 patients (48.4% male patients) with a mean age of 25.4 ± 7.1 years were included. The overall prevalence of MCL (sMCL and dMCL) injuries and isolated dMCL injuries was 16.5% (42 of 254) and 24.8% (63 of 254), respectively. No isolated sMCL injuries were found. Posterior oblique ligament injuries were found in 12 patients (4.7%) with MCL (sMCL and dMCL) injuries. An LM injury (odds ratio [OR], 3.94; 95% confidence interval [CI], 1.73-8.94; P= .001) and LFC impaction (OR, 2.37; 95% CI, 1.11-5.07; P= .02) increased the odds of having an MCL injury, whereas an MM injury (OR, 0.26; 95% CI, 0.12-0.59; P= .001) reduced the odds. Isolated dMCL injuries were significantly associated with MFC bone bruising (OR, 4.21; 95% CI, 1.92-9.25; P < .001) and LFC impaction (OR, 3.86; 95% CI, 1.99-7.49; P < .001). The overall combined prevalence of MCL (sMCL and dMCL) injuries and isolated dMCL injuries in patients with ACL tears was high (16.5%+ 24.8%= 41.3%). The presence of an LM injury and LFC impaction increased the odds of having an MCL injury, whereas the presence of an MM injury reduced the odds. MFC bone bruising and LFC impaction were associated with the presence of isolated dMCL injuries. Level III, retrospective cohort study.

High prevalence of meniscal ramp lesions in anterior cruciate ligament injuries

PurposeTo evaluate the prevalence of and factors associated with meniscal ramp lesions on magnetic resonance imaging (MRI) in patients with anterior cruciate ligament (ACL) injuries.MethodsData from the Natural Corollaries and Recovery after ACL injury multicentre longitudinal cohort study (NACOX) were analysed. Only patients who underwent MRI were included in this study. All MRI scans were reviewed by an orthopaedic knee surgeon and a musculoskeletal radiologist. The patients were divided into two groups, those with and without ramp lesions according to MRI findings. Univariable and stepwise forward multiple logistic regression analyses were used to evaluate patient characteristics (age, gender, body mass index, pre-injury Tegner activity level, activity at injury) and concomitant injuries on MRI (lateral meniscus, medial collateral ligament [MCL], isolated deep MCL, lateral collateral ligament, pivot-shift-type bone bruising, posteromedial tibial [PMT] bone bruising, medial femoral condyle bone bruising, lateral femoral condyle [LFC] impaction and a Segond fracture) associated with the presence of meniscal ramp lesions.ResultsA total of 253 patients (52.2% males) with a mean age of 25.4 ± 7.1 years were included. The overall prevalence of meniscal ramp lesions was 39.5% (100/253). Univariate analyses showed that contact sports at ACL injury, pivot-shift-type bone bruising, PMT bone bruising, LFC impaction and the presence of a Segond fracture increased the odds of having a meniscal ramp lesion. Stepwise forward multiple logistic regression analysis revealed that the presence of a meniscal ramp lesion was associated with contact sports at ACL injury [odds ratio (OR) 2.50; 95% confidence intervals (CI) 1.32–4.72; P = 0.005], pivot-shift-type bone bruising (OR 1.29; 95% CI 1.01–1.67; P = 0.04), PMT bone bruising (OR 4.62; 95% CI 2.61–8.19; P < 0.001) and the presence of a Segond fracture (OR 4.38; 95% CI 1.40–13.68; P = 0.001).ConclusionThe overall prevalence of meniscal ramp lesions in patients with ACL injuries was high (39.5%). Contact sports at ACL injury, pivot-shift-type bone bruising, PMT bone bruising and the presence of a Segond fracture on MRI were associated with meniscal ramp lesions. Given their high prevalence, meniscal ramp lesions should be systematically searched for on MRI in patients with ACL injuries. Knowledge of the factors associated with meniscal ramp lesions may facilitate their diagnosis, raising surgeons’ and radiologists’ suspicion of these tears.Level of evidenceIII.

Treatment decision-making process after an anterior cruciate ligament injury: patients’, orthopaedic surgeons’ and physiotherapists’ perspectives

ObjectiveTo investigate the treatment decision-making process after an anterior cruciate ligament (ACL) injury from patients’, orthopaedic surgeons’ and physiotherapists’ perspectives.MethodsThe study is a part of the NACOX study, which is designed to describe the natural corollaries after ACL injury. For the present study, a subgroup 101 patients were included. Patients, their orthopaedic surgeons and their physiotherapists, answered a Shared Decision-Making Process (SDMP) questionnaire, when treatment decision for ACL reconstruction surgery (ACLR) or non-reconstruction (non-ACLR) was taken. The SDMP questionnaire covers four topics: “ informed patient”, “ to be heard”, “ involvement” and “ agreement”.ResultsMost (75–98%) patients considered their needs met in terms of being heard and agreement with the treatment decision. However, fewer in the non-ACLR group compared to the ACLR group reported satisfaction with information from the orthopaedic surgeon (67% and 79%), or for their own involvement in the treatment decision process (67% and 97%).Conclusion and practice implicationsMost patients and caregivers considered that patients’ needs to be informed, heard and involved, and to agree with the decision about the treatment process, were fulfilled to a high extent. However, patients where a non-ACLR decision was taken experienced being involved in the treatment decision to a lower extent. This implies that the non-ACLR treatment decision process needs further clarification, especially from the patient involvement perspective.

Shunned and Admired: Montessori, Self-Determination, and a Case for Radical School Reform

School reform is an important national and international concern. The Montessori alternative school system is unique in that it is well-aligned with the science of healthy development and learning, has strong social–emotional and academic outcomes, is virtually unchanged in over a century, can be applied across all the school years, and still attracts considerable attention and allegiance—yet it remains “on the margins” (Whitescarver and Cossentino Teachers College Record, 110, 2571–2600, 2008) of the bulwark educational system, as often shunned as admired. Why does Montessori persist (and increasingly in the public sector) and why does it elicit such sharply contrasting reactions? This article reviews several reasons why it is admired, such as evidence of Montessori’s effectiveness, its alignment with educational psychology research, and its broad scope. The points of research alignment are presented as natural corollaries of Montessori’s central premise: independence, or self-determination. After discussing these extrinsic and intrinsic reasons why Montessori is admired, the article concludes with speculation as to why it is also shunned—namely its incommensurability with conventional education culture and what might be a consequence: frequent poor implementation. The incommensurability of evidence-based alternatives with the conventional system is also posed as a reason for radical school reform.

Natural corollaries and recovery after acute ACL injury: the NACOX cohort study protocol

IntroductionAnterior cruciate ligament (ACL) injury can result in joint instability, decreased functional performance, reduced physical activity and quality of life and an increased risk for post-traumatic osteoarthritis. Despite the development...

Universal algebra for general aggregation theory: Many-valued propositional-attitude aggregators as MV-homomorphisms

This article continues Dietrich and List's (2010) work on propositional-attitude aggregation theory, which is a generalized unification of the judgement aggregation and probabilistic opinion-pooling literatures. We first propose an algebraic framework for an analysis of (many-valued) propositional-attitude aggregation problems. Then we shall show that systematic propositional-attitude aggregators can be viewed as homomorphisms—algebraically structure-preserving maps—in the category of Chang's (1958a, Trans. Am. Math. Soc., 88, 467–490) MV-algebras. (Proof idea: Systematic aggregators are induced by maps satisfying certain functional equations, which in turn can be verified to entail homomorphy identities.) Since the 2-element Boolean algebra as well as the real unit interval can be endowed with an MV-algebra structure, we obtain as natural corollaries two famous theorems: Arrow's theorem for judgement aggregation as well as McConway's (1981, J. Am. Stat. Assoc., 76, 410–414) characterization of linear opinion pools. Conceptually, this characterization of aggregators can be seen as justifying a certain structuralist interpretation of social choice. Technically and perhaps more importantly, it opens up a new methodology to social-choice theorists: the analysis of general aggregation problems by means of universal algebra.

On groups whose word problem is solved by a$tilde;counter automaton

We prove that a group G has a word problem that is accepted by a deterministic counter automaton with a weak inverse property if and only if G is virtually abelian. We extend this result to larger classes of groups by considering a generalization of finite state automata, counter automata and pushdown automata. Natural corollaries of our general result include a restricted version of Herbst's classification of groups for which the word problem is a one counter language and a new classification of automata that accept context-free word problems.

On groups whose word problem is solved by a~counter automaton

We prove that a group G has a word problem that is accepted by a deterministic counter automaton with a weak inverse property if and only if G is virtually abelian. We extend this result to larger classes of groups by considering a generalization of finite state automata, counter automata and pushdown automata. Natural corollaries of our general result include a restricted version of Herbst's classification of groups for which the word problem is a one counter language and a new classification of automata that accept context-free word problems.

Characterization of an auto-compatible default theory

In this paper, an equivalence condition for deciding whether a default theory is an auto-compatible default one is presented. Under the condition, the existence of extension of an auto-compatible default theory is a natural result. By introducing a well-ordering over the set D of default rules, the extensions of an auto-compatible default theory (D, W) can be computed directly. The condition represents clearly the characterization of an auto-compatible default theory, and some properties about auto-compatible default theory, such as semi-monotonicity, become natural corollaries. Based on the characterization, the revision of default beliefs is discussed to ensure the existence of extension of the default theory, and the method is applied to investigate stable models of a general logic program.

A Derivation of a Useful Consequence of the Gauss-Markov Theorem

Abstract The Gauss-Markov (GM) theorem and its many consequences are well known. It has been our experience that graduate students in linear model courses benefit substantially by deriving these consequences, all of which form natural corollaries to the GM theorem. In deriving any one lemma, the student is compelled to reuse many other GM-based lemmas. In this article we present another example of such a lemma that arises in the forward-elimination variable selection procedure. The derivation given is considered to be pedagogically useful.

Functional Dependencies in a Relational Database and Propositional Logic

An equivalence is shown between functional dependency statements of a relational database, where → has the meaning of determines, and implicational statements of propositional logic, where⇒ has the meaning of implies. Specifically, it is shown that a dependency statement is a consequence of a set of dependency statements if the corresponding implicational statement is a consequence of the corresponding set of implicational statements. The database designer can take advantage of this equivalence to reduce problems of interest to him to simpler problems in propositional logic. A detailed algorithm is presented for such an application. Two proofs of the equivalence are presented: a proof and a proof. The syntactic proof proceeds in several steps. It is shown that 1) Armstrong's Dependency Axioms are complete for dependency statements in the usual logical sense that they are strong enough to prove every consequence, and that 2) Armstrong's Axioms are also complete for implicational statements in propositional logic. The equivalence then follows from 1) and 2). The other proof proceeds by considering appropriate semantic interpretations for the propositional variables. The Delobel-Casey Relational Database Decomposition Theorems, which heretofore have seemed somewhat fortuitous, are immediate and natural corollaries of the equivalence. Furthermore, a counterexample is demonstrated, which shows that what seems to be a mild extension of the equivalence fails.

Management Science and Management: Implementing Management Science Via Situational Normativism

Implementation of management science via situational normativism, a descriptive-normative approach to decision making, is discussed. The situational normativism process involves a search by manager and management scientist for a synthesized situational frame of understanding (involving analytic and heuristic knowledge, as discussed in the paper) within which solutions to the decision situation problem can be found. Implementation constraints (e.g., cognitive style constraints and political constraints) are explicitly considered. A situational normativism organization development concept is suggested. Mutual understanding between scientist and manager evolves from and is fed to the situational normativism search process. Unity of science and management, implementation, and organization (system) development—in the sense of attaining evolved-in-the-process goals—are viewed as natural corollaries of working towards a synthesized situational frame of understanding via situational normativism. Some examples illustrating aspects of the organization development concept arising from practice are presented.