Exploratory or confirming study?

Methodology is hard. And making valid inferences is very hard. With regard to these topics, orthopaedic research is not very different to other field in medicine. It means that misconceptions, misunderstandings and flawed approaches are prevalent also in our field. American Journal of Sports Medicine published recently two papers which both made a quite common, […]

Treatment outcomes and shared decision making

Key points Clinical equipoise will become more common in orthopaedics When treatment outcomes are subjective and have large heterogeneity, shared decision making should be used Clinical equipoise means a situation when there is no objective superiority between two choices. The lack of superiority may be due to complete lack of data or evidence about certain […]

Population health and orthopaedic surgeries

Both knee arthroscopy for partial meniscectomy and shoulder arthroscopy for acromioplasty were very common procedures few years back in orthopaedic surgery. During the first two decades of this millennium extensive amount of research has been published showing that the effect of these procedures to treat knee and shoulder pain and function is quite weak. Despite […]

Propensity scores, orthopaedics and shared decision making

This is something I posted on Twitter last October. Extended discussion can be found below the tweets Propensity score matching is often used when two cohorts of patient are compared. Aim is to have somewhat comparable groups so effect of treatment or intervention could be estimated reliably. In short, two groups of patient tread by […]

Uncertainty in medical decision making

“The failure to train doctors about clinical uncertainty has been called “the greatest deficiency of medical education throughout the twentieth century.” Djulbegovic (2004), https://www.bmj.com/content/329/7480/1419 Life is full of uncertainties. In decision making uncertainty means that it is impossible to define future outcomes. Amount of medical information continues to grow exponentially, but uncertainty is still inevitable […]

No evidence of no evidence

In the null hypothesis significance testing framework, failure to reject the null is never evidence in support of null. However, it is extremely common that failure to reject the null, ie. getting a p-value larger 0.05 is interpreted as “no difference” or “no evidence”. As many experts have said, “absence of evidence is not evidence […]

Industry based evidence synthesis

In 2017, me and colleagues published both a literature and registry based analysis of use of metal-on-metal hip replacements. This study, titled Lack of evidence—the anti-stepwise introduction of metal-on-metal hip replacements, was a hypothesis-driven study since at that time it seemed that the use of ASR hip replacements was not that evidence based but mainly […]

Declining incidence of MoM revision surgeries

Our recent study investigating annual trends of revision surgeries in patients with MoM hip replacements was recently published in the Journal of Arthroplasty (www). Here is the GrAbstract of the study: This study is of great importance because it is the largest non-registry based study investigating what sort of trends the number of revision surgeries […]

Post-hoc power – Alone in the universe

Prologue Firstly, it is important to describe what post-hoc power really means. Post-hoc power is the power of the test using effect size observed and sample size used in the study. For this reason post-hoc power is often labeled as observed power. If for any experiment the effect size, parameter estimates and sample size is […]