Diagnostic heterogeneity in deltoid ligament repair studies: Implications for evidence synthesis.

Abstract

Despite numerous comparative studies and meta-analyses, the role of deltoid ligament repair in acute rotational ankle fractures remains unresolved. Systematic reviews consistently report statistical heterogeneity that exceeds interpretable thresholds, while functional outcomes appear equivocal. Previous reviews have documented diagnostic variability across studies, but the implications of this heterogeneity for evidence synthesis have not been fully examined. This narrative review examines how variability in defining deltoid ligament injury and medial instability may render studies non-comparable, thereby limiting meaningful evidence synthesis. Published systematic reviews document substantial variation in how deltoid ligament injury and medial instability are defined. Medial clear space cutoffs range from >1 mm to >6 mm across studies, stress techniques differ, and the timing of assessment varies from pre-fixation to post-fixation without standardization. Systematic reviews and meta-analyses consistently report statistical heterogeneity that exceeds comfortable interpretability thresholds, while functional outcomes show small, inconsistent, or absent differences despite occasional radiographic improvements. Studies that reassess medial stability after anatomic fixation remain a minority. The diagnostic heterogeneity documented in deltoid ligament repair literature limits comparability across studies and complicates interpretation of pooled analyses. When studies use different definitions, thresholds, and timing of assessment, they may not be examining the same clinical condition. This review does not claim that heterogeneity caused the debate, nor that any particular solution improves outcomes. Rather, it argues that diagnostic standardization should precede further therapeutic comparison if meaningful evidence synthesis is to be possible. A verification-first framework-reassessing medial stability after anatomic fixation-is proposed as a testable methodological hypothesis. Its clinical utility requires prospective validation.