Mallet-Like Distal Phalanx Base Injuries in Children and Adolescents: A PRISMA-ScR Scoping Review and a Proposed, Unvalidated Phenotype-Based Assessment Framework

Background/Objectives: A mallet-like posture in a child or adolescent can represent a closed tendon or dorsal avulsion injury, but it may instead signal a physeal or juxtaphyseal distal-phalanx fracture that communicates with the nail unit. We mapped the diagnostic and management evidence and developed a proposed phenotype-based assessment framework whose clinical performance has not been validated. Methods: Following Joanna Briggs Institute (JBI) guidance and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR), PubMed and OpenAlex were searched without date restrictions through 22 July 2026, with citation chasing and organizational-website searching. Two human reviewers independently screened titles/abstracts and assessed potentially eligible reports; disagreements were resolved by discussion and consensus. One reviewer charted standardized data and a second verified the displayed fields. Results: The historical search yielded 219 database occurrences and 161 unique records. After 84 title/abstract exclusions, 77 database reports were assessed; 26 were excluded and 51 included. Other methods contributed nine sources, yielding 60 included sources. Evidence was predominantly retrospective and heterogeneous. Immobilization duration was not comprehensively synthesized in this review; therefore, no universal duration is proposed. No diagnostic-accuracy study, formal certainty grade, universally supported antibiotic regimen, or validated fixation threshold was identified. Conclusions: Nail-unit findings can raise concern for communication and support urgent specialist assessment under local protocols. Closed, congruent, stable mallet injuries may be considered for splinting after a complete nail-unit examination. The framework is proposed and unvalidated.