Congenital musculoskeletal and limb deformities (CMLD) remain one of the most visible yet under-prioritized birth defects, generating lifelong disability, stigma and economic loss; fresh GBD 2021 estimates now map incidence, prevalence, deaths and disability-adjusted life-years (DALYs) for children under five across 204 territories from 1990 to 2021, revealing both encouraging global declines and widening relative inequality. Worldwide incident cases fell modestly from 2.52 to 2.44 million, pushing incidence down from 407 to 370 per 100 000 (EAPC −0.2%), while prevalent cases decreased only marginally; sharper improvements were seen in health loss, with DALYs dropping 27% to 258 per 100 000 and mortality falling 37% to 168 per million, signalling better survival and functional care. These headline trends, however, mask striking heterogeneity linked to socio-demographic index (SDI): low-SDI settings still record the highest incidence (466 per 100 000) and DALYs (367), whereas high-SDI countries report less than half those rates, and middle-SDI regions achieved the steepest annual reductions (−0.5% incidence, −1.6% DALYs).
Geographically, Southern Latin America, Brunei, Guatemala and Honduras now exceed 600 incident cases per 100 000 preschoolers, while Central Europe and several Pacific islands fall below 230; prevalence peaks above 1 500 per 100 000 in high-income Asia-Pacific nations, reflecting advanced diagnostics and longer survival rather than higher birth prevalence. Sub-Saharan Africa carries the heaviest health loss—Southern Sub-Saharan Africa tops DALYs (412) and mortality (3.6 per 100 000)—whereas East Asia and high-income Asia-Pacific recorded the fastest mortality decline (> 6% per year). Caribbean, Central Asian and Western European regions bucked the global downward trend, showing recent upticks in incidence and prevalence, probably driven by improved registration, assisted-reproduction technologies and maternal metabolic risk factors.
Across the five SDI quintiles every indicator improved in absolute terms during 1990-2021, yet relative inequality deteriorated: concentration indices for mortality shifted from −0.37 to −0.46, indicating that deaths are increasingly concentrated in disadvantaged countries. Slope-inequality analysis shows that low-SDI nations still shoulder 220 extra incident cases and two extra deaths per million children compared with high-SDI peers, gaps that have narrowed only slightly over three decades. EAPC correlations expose the paradox that countries starting with higher SDI achieved faster DALY and mortality declines, underscoring the compounding benefits of strong antenatal services, surgical capacity and rehabilitation.
Country-level trajectories diverge dramatically. Equatorial Guinea, Serbia and South Korea slashed incidence by > 1.5% annually, while Spain, Georgia and Ireland posted increases > 1.4%; Afghanistan retains by far the highest DALY and death rates (> 700 and 620 per million), contrasting with < 200 DALYs in most of Western Europe. China, Estonia and the Czech Republic drove mortality down more than 6% yearly, but Dominica, Ecuador and Turkmenistan saw rises above 2%, highlighting the consequences of conflict, economic shocks and fragile perinatal health systems.
Limitations accompany these insights. GBD modelling relies on sparse vital-registration data in the very regions where CMLD is most common; under-ascertainment of mild limb anomalies and late-presenting spine deformities may bias estimates downward, while varying ICD coding practices complicate cross-country comparisons. Nevertheless, the 32-year dataset offers the clearest picture to date of how poverty, nutrition, infection control and access to prenatal diagnosis shape the onset and lifelong impact of musculoskeletal birth defects.
Policy implications are urgent. Absolute numbers remain high—almost 2.5 million new cases and 11 000 preventable deaths annually—while widening relative gaps violate universal-health-coverage principles. Proven bundles including folic-acid food fortification, rubella vaccination, diabetes and obesity management in pregnancy, and ultrasound screening can cut incidence and complications, yet coverage is lowest where needs are greatest. Surgical networks, prosthetics and community-based rehabilitation must expand in low-SDI settings to convert survival gains into functional gains; without such investment, declining mortality will simply enlarge the pool of children living with untreated limb deficiency or arthrogryposis, perpetuating disability and socioeconomic exclusion. Targeted financing, technology transfer and South-South collaboration are therefore essential to bend both the epidemiological curve and the equity gradient for congenital musculoskeletal and limb deformities before 2030.

DOI
10.1007/s11684-025-1156-0