A meaningful unit could be a composite index combining clinical activity, research output, training capacity, and international cooperation. Alternatively, one might imagine a symbolic measure—a single “unit” representing any surgeon, team, or country committed to advancing musculoskeletal health through care, education, and shared knowledge. In this way, the map of global orthopedics could be redrawn not by borders, but by impact. However, it would be impossible to put each orthopedic challenge on the same map.

In schematic terms, the first approximation in the representation that we can use can be generated by applying a population-weighted distortion to the world map (Fig. 2) to illustrate the distribution of human hips in the world [1]. The primary variable of interest is population. To accurately reflect the incidence relative to population size, the cartogram assigns equal spatial representation to each individual (density of population), based on a total global population of eight billion. Consequently, the geographical boundaries are expanded or compressed in proportion to each country’s population. This results in a map that diverges significantly from conventional geographic projections typically used in educational contexts.

Fig. 2

Representation of the number of hips in the world population according to the regions of the world concerned

As seen on this distorted map (or anamorphism), India, often underestimated on world maps, stands out prominently here on this cartogram because it is the most populous area in the world after China, with more than 1.5 billion inhabitants. In contrast, North America (Canada in dark blue), similar to Russia (in yellow), experiences significant anamorphic distortion due to its low population density—approximately 3.3 inhabitants per square kilometer. The United States, which has a higher average density of about 34 inhabitants per square kilometer, appears less distorted. In Western Europe, most countries seem enlarged, except for the largest ones, such as France and Spain. Their apparent size is tempered by relatively lower population densities (100 inhabitants per square kilometer, two to four times less than their neighbours, including the Netherlands, Germany, and the United Kingdom). South America comes across as considerably compressed, with its 18 million square kilometers home to only about 400 million people, indicating a comparatively low density. In Africa, population density varies widely by country, from fewer than three inhabitants per square kilometer in nations like Namibia and Botswana to over 430 inhabitants per square kilometer in countries such as Rwanda. As can be seen, one fracture of the femoral neck is a problem that carries a risk of necrosis or pseudoarthrosis. Still, millions of fractures are merely a geographical or statistical representation.

Difficulties in defining equivalence for diseases

The first person to use maps for medical epidemiology was probably Jon Snow [2], who studied a cholera epidemic in 1854 in Soho, London, that killed more than 500 people in ten days. Jon Snow observed that the deaths were clustered around a public water pump on Broad Street (Fig. 3), which supplied residents with drinking water. By marking each death with a black dash on a map of Soho, Snow quickly identified the source of the cholera epidemic: the public water pump on Broad Street.

Fig. 3

First epidemic map (1854)

The study of the spatial distribution and spread of diseases has proven essential, particularly for illnesses such as malaria, AIDS, and more recently, COVID-19. This type of geographical representation is also undeniably valuable for understanding global orthopaedic conditions.

One of the significant challenges of creating epidemic maps before the advent of computers was representing the actual surface area of landmasses. The commonly used Mercator projection (Fig. 4) significantly distorted reality, exaggerating the size of certain territories, such as Russia and Canada, while minimizing others, like Africa. Some cartographers, including Buckminster Fuller, attempted to address this issue. Fuller [3] projected the Earth onto 20 triangular faces of a regular icosahedron, a geometric shape closely approximating a sphere (Fig. 5) and thus limiting distortion. This icosahedral projection, which could be unfolded and flattened like an origami figure, gave Africa (Fig. 6) its correct proportional size relative to Eurasia, North America, and China. Such projections can be particularly useful for representing data like population density per square kilometer: for example, India and Africa have a similar population, but not the same size.

Fig. 4

Mercator-style geography often seen in medical politics and academic circles, where institutional power, publication metrics, or funding disparities distort influence

Fig. 5

Fuller map with a minimum distortion of surfaces

Fig. 6

The size of Africa compared to other areas and the number of orthopaedic surgeons in Fig. 7

Construction of Anamorphisms

The use of computer-generated population cartograms in medical mapping was first introduced in the United States by Selvin and colleagues in the mid-1980s [4–5]. However, their potential remained largely underappreciated at that time, primarily due to the technical challenges of generating cartograms and the perception of their arbitrary nature. Unlike the distortions of the Mercator projection, which magnify some regions while diminishing others, this new perspective values each country based on surface representation. Introducing new computational tools, particularly artificial intelligence [6], has greatly simplified the process of assigning values to specific variables—such as the distribution of orthopedic surgeons worldwide (Fig. 7)—considering factors like the number of surgeons in each country and the country’s surface area.

Fig. 7

Map of the number of orthopedists by region

Emerged land (all countries) occupies a constant surface area, as does the global ocean. When a figure (a raw value) is assigned to each country, the algorithm produces a balancing of “densities” by assigning each country a percentage of the land area proportional to the indicator value. The algorithm treats the original raw values as each country’s contribution to the total land area, occasionally transforming them into relative values. The shape of the countries is clearly modified each time. In addition to the presence of orthopaedic surgeons in Egypt and North Africa—particularly in Morocco, Tunisia, and Algeria—the African continent faces a significant shortage of orthopaedic surgeons [7] compared to the rest of the world (Fig. 7). We can also note that three other large countries (Canada, in dark blue, Russia in pink, and Australia) have a low density of orthopaedic surgeons, resulting in challenges that can be anticipated for fractured patients needing to reach a surgeon across long distances.

The sea poses a problem for maps of this type: since the areas are proportional to raw statistical values ​​and we obviously have no data for the sea (by construction, the corresponding figure is zero), logically the seas should be invisible. However, for the reader, it is very useful to see the seas preserved with their respective areas. The seas are therefore assigned a neutral value (neutral buoyancy), which helps preserve the shapes of the coasts. This makes countries more recognizable and the maps more readable. Readability is a crucial element of communication for orthopaedic surgeons.

Reading a map with anamorphism

Comparing the positions held by various countries on different maps can lead to absurdities. For instance, the paper by Wu et al. [8], which examines publications on conservative treatment for osteonecrosis worldwide (Fig. 8), seems to imply that, on a Mercator projection, osteonecrosis is found only in certain regions of the world. However, considering osteonecrosis related to sickle cell disease [9,10,11], the current population of Africa is 1,546,654,537, with 20% of that population affected by sickle cell disease and a prevalence of 50% for osteonecrosis among those with the condition. Therefore, the number of osteonecrosis cases in Africa could reach as high as 154,665,453, presenting a completely different picture on another map (Fig. 9), and likely the largest number of osteonecrosis cases worldwide.

Fig. 8

Top countries for hip-preserving treatment in early osteonecrosis

Fig. 9

Cases of hip osteonecrosis related to sickle cell disease. The area of ​​each country is proportional to the number of people with sickle cell disease

Strictly speaking, the reading only makes sense map by map: it reads the global distribution of one variable and one only. The maps function like a series of pie charts, each displaying a specific indicator for each country’s share of the global total. Each anamorphism is therefore unique; it cannot represent another variable [12,13,14].

Orthopaedic challenges represented by orthopaedic word maps

The musculoskeletal system includes bones, the joints that connect them, and the muscles responsible for generating movement. This system enables essential functions such as self-care, work, and leisure activities. It is vulnerable to a wide range of disorders, which are highly prevalent; approximately 30% of the world’s population is affected by musculoskeletal conditions. The burden of these diseases is significant and continues to increase [15]. Among individuals over the age of 65, more than half experience musculoskeletal issues, largely due to age-related joint degeneration, leading to conditions such as osteoarthritis (OA), spinal pain, and fractures.

With an aging population and obesity, degenerative disorders now account for the majority of musculoskeletal diseases. While the impact varies, approximately 80% of individuals with OA experience reduced mobility, and 25% are unable to perform everyday tasks.

Of course, every orthopaedic condition presents its own challenges. However, two of the most pressing issues today are, first, the appropriate management of patients with obesity—a condition that is unevenly distributed across populations (Fig. 10)—and second, the impact of disasters and armed conflicts around the world [16]. These crises, which are also unevenly distributed (Fig. 11), are major contributors to traumatic injuries such as fractures and amputations, often resulting in significant shortages of medical equipment and resources.

Fig. 10

Map of obesity distribution in the world

Fig. 11

Traumatic injuries related to war and disasters

Education and research in orthopaedics.

The approach to managing musculoskeletal disorders and injuries is continually evolving, driven by advances in knowledge and technology. Healthcare professionals must stay current with these developments to provide optimal patient care. Musculoskeletal education is a lifelong process, beginning with undergraduate medical studies, progressing through postgraduate specialty training, and often culminating in subspecialisation. After graduation, Continuing Medical Education (CME) ensures that orthopaedic surgeons remain informed about the latest medical advancements, particularly with orthopaedic meetings and journals [17].

Education is nearly absent in some parts of the world (Fig. 12). But it is worth noting that in developed countries such as Canada, it's education is strong, however, when it comes to research, this country lag behind compared to other regions, such as USA and Japan (Fig. 13), for research activity. Research in Orthopaedics and Traumatology is highly diverse, reflecting the presence of multiple submarkets that are each at different stages of the product life cycle and therefore require varying levels of investment. Assessments are often needed for new products, novel manufacturing techniques, and evolving clinical practices. Tools such as patent databases and literature analyses are commonly used to identify trends in industrial research and innovation. However, in a globalized economy, international patent records often reflect the location of a company’s headquarters rather than the true origin of the research.

Fig. 12

Relative importance of countries in Orthopaedic Education and training of Professionals

Fig. 13

Research in orthopedics, trauma, and industrial property rights regarding patents in orthopaedics. The surface area of each country is proportional to the money for research and patents