PURPOSE: To identify and evaluate the diagnostic criteria used to define and diagnose hip microinstability.
METHODS: A systematic review was conducted in accordance with Preferred Reporting Items for Systematic Review and Meta-Analyses guidelines. PubMed, Cochrane Central Register of Controlled Trials, and Scopus were searched using the keywords "hip" AND "microinstability." Studies were included that reported diagnostic criteria for hip microinstability. Exclusion criteria included review articles, technique papers, biomechanical studies, cadaveric studies, and studies focused on traumatic instability. Diagnostic criteria were categorized into 4 primary domains: physical examination findings (16 studies), intraoperative findings (17 studies), radiographic criteria (6 studies), and clinical history (1 study).
RESULTS: Twenty-three studies met inclusion criteria (Levels II-IV). The most frequently cited criteria were ease of hip distraction during arthroscopy (14 studies), a positive hyperextension-external rotation test (13 studies), and a positive prone external rotation test (8 studies). Substantial variability in diagnostic approaches was observed, with no universally applied diagnostic framework.
CONCLUSIONS: There remains substantial variability in the diagnostic criteria for hip microinstability. Ease of intraoperative distraction and physical examination findings are the most consistently cited.
LEVEL OF EVIDENCE: Level IV, systematic review of Level II to IV studies.