Historic indications for fixation of posterior malleolus fractures- where did they come from and where are we now?

INTRODUCTION: The indications for reduction and fixation of the posterior malleolus component of rotational ankle fractures have been controversial for nearly a century. This study aims to identify the historical basis for surgical intervention and trace trends in management strategies over time. METHODS: In March 2023, a systematic review of full-text, English-language articles providing indications for surgical fixation of the posterior malleolus component of rotational ankle fractures was performed. Articles underwent title and abstract screening before undergoing full-text review. RESULTS: Historical indications for surgical fixation were size-dependent, with fractures comprising 25 % to 33 % of the plafond recommended for internal fixation. Modern studies suggest that nonoperative management of posterior malleolus fractures below this threshold results in residual malreduction of the articular surface, syndesmotic instability, and an increased need for independent fixation of the syndesmosis. CONCLUSIONS: Size-based indications for posterior malleolus fracture fixation are based on Level V evidence from small retrospective case series published nearly one century ago and should be retired. While the size of the posterior malleolus component cannot be ignored, additional factors like fracture morphology and location within the plafond should guide modern surgical indications. Contemporary studies indicate that reduction and fixation of small posterior malleolus fractures (comprising less than 25 % of the articular surface) are associated with improved articular reductions, tibiotalar contact pressures, syndesmotic stability with decreased need for independent fixation of the syndesmosis, and superior postoperative outcomes.

Identification of the Human Skeletal Stem Cell.

Stem cell regulation and hierarchical organization of human skeletal progenitors remain largely unexplored. Here, we report the isolation of a self-renewing and multipotent human skeletal stem cell (hSSC) that generates progenitors of bone, cartilage, and stroma, but not fat. Self-renewing and multipotent hSSCs are present in fetal and adult bones and can also be derived from BMP2-treated human adipose stroma (B-HAS) and induced pluripotent stem cells (iPSCs). Gene expression analysis of individual hSSCs reveals overall similarity between hSSCs obtained from different sources and partially explains skewed differentiation toward cartilage in fetal and iPSC-derived hSSCs. hSSCs undergo local expansion in response to acute skeletal injury. In addition, hSSC-derived stroma can maintain human hematopoietic stem cells (hHSCs) in serum-free culture conditions. Finally, we combine gene expression and epigenetic data of mouse skeletal stem cells (mSSCs) and hSSCs to identify evolutionarily conserved and divergent pathways driving SSC-mediated skeletogenesis. VIDEO ABSTRACT.