Background The purpose of this study is to assess the epidemiology, population-specific treatment trends, and complications of distal radius fractures in the United States. Methods The PearlDiver database (Humana [2007–2014], Medicare [2005–2014]) was used to access US inpatient and outpatient data for all patients who had undergone operative and nonoperative treatment for a distal radius fracture in the United States. Epidemiologic analysis was performed followed by age-based stratification, to assess prevalence, treatment trends, and rates of complications. Results A total of 1,124,060 distal radius treatment claims were captured. The incidence of distal radius fractures follows a bimodal distribution with distinct peaks in the pediatric and elderly population. Fractures in the pediatric population occurred predominately in males, whereas fractures in the elderly population occurred more frequently in females. The most commonly used modality of treatment was nonoperative; however, the use of internal fixation increased significantly during the study period, from 8.75 to 20.02%, with a corresponding decrease in percutaneous fixation. The overall complication rate was 8.3%, with mechanical symptoms most frequently reported. Conclusions The last decade has seen a significant increase in the use of internal fixation as treatment modality for distal radius fractures. The impetus for this change is likely multifactorial and partly related to recent innovations including volar locking plates and an increasingly active elderly population. The implicated financial cost must be weighed against the productivity cost of maintaining independent living to determine the true burden to the healthcare system.

Level III: retrospective comparative study.

Most bones in mammals display a limited capacity for natural large-scale repair. The ribs are a notable exception, yet the source of their remarkable regenerative ability remains unknown. Here, we identify a Sox9-expressing periosteal subpopulation that orchestrates large-scale regeneration of murine rib bones. Deletion of the obligate Hedgehog co-receptor, Smoothened, in Sox9-expressing cells prior to injury results in a near-complete loss of callus formation and rib bone regeneration. In contrast to its role in development, Hedgehog signaling is dispensable for the proliferative expansion of callus cells in response to injury. Instead, Sox9-positive lineage cells require Hh signaling to stimulate neighboring cells to differentiate via an unknown signal into a skeletal cell type with dual chondrocyte/osteoblast properties. This type of callus cell may be critical for bridging large bone injuries. Thus despite contributing to only a subset of callus cells, Sox9-positive progenitors play a major role in orchestrating large-scale bone regeneration.Editorial note: This article has been through an editorial process in which the authors decide how to respond to the issues raised during peer review. The Reviewing Editor's assessment is that all the issues have been addressed (<xref ref-type="decision-letter" rid="SA1">see decision letter</xref>).