FP15.1 An international multidisciplinary Consensus on Hip Instability Management Evaluation - CHIME

Abstract ICLB15 - The Preservation Scorecard: Fundamentals of Tracking Outcomes and Standardizing Recovery, Session Room 12 (BMCC Level 3), October 9, 2026, 14:00 - 16:00 Introduction Diagnosing hip instability remains challenging due to its multifactorial nature. Although progress has been made in understanding its biomechanical basis and identifying clinical signs and imaging techniques, there is no consensus on the most relevant indicators or diagnostic thresholds. To address this gap, we conducted a Delphi consensus study with an international panel of experts to establish standardized clinical statements across three domains: biomechanical features, clinical assessment, and imaging characteristics of hip instability. Methods A modified Delphi consensus study was conducted in accordance with the ACcurate COnsensus Reporting Document (ACCORD) guideline. The consensus meeting took place during the 15th Symposium on Joint Preserving and Minimally Invasive Surgery of the Hip in Quebec City, Canada (June 2025). A multidisciplinary steering committee and 58 international experts from nine countries participated. Following a scoping review, statements addressing biomechanics, clinical assessment, and imaging were developed and refined through two Delphi rounds using structured online surveys. Consensus was defined as ≥75% agreement. Results Key anatomic contributors to instability included bony morphology, static stabilizers (labrum and capsule), and dynamic muscular stabilizers. Femoral head translation >3 mm was considered abnormal. There was insufficient evidence to distinguish micro-instability from conventional instability. Clinically, consensus symptoms included anterior hip pain during daily activities (sitting, squatting, sports), mechanical symptoms (popping, clicking, grinding), and subjective instability. Female sex and borderline hip dysplasia were identified as key risk factors. Strong agreement supported the use of radiography (AP pelvis, false-profile, Dunn view), MRI, and CT as foundational imaging modalities, with selective use of cartilage mapping and dynamic ultrasound. Consensus morphologic parameters included lateral center-edge angle (LCEA), anterior and posterior wall indices (AWI, PWI), and Tönnis angle. Key thresholds were LCEA <20°, AWI <0.30, and acetabular version <5° or >30°. No consensus was reached for emerging metrics such as the FEAR index, crescent sign, anterior capsule thickness, or dynamic translation. Discussion These findings provide an evidence-based framework for evaluating hip instability. However, current diagnostic measures remain heterogeneous, limiting consistent classification. Improved, reproducible three-dimensional in vivo assessments are needed to better distinguish physiological laxity from pathological instability. While consensus was achieved for key imaging parameters, uncertainty persists regarding newer soft tissue and dynamic measures, highlighting priorities for future research.