Importance and evidence of stress radiography in the diagnostics of ligamentous knee joint instability

Briese T; Deichsel A; Laky B; Ackermann J; Muench LN; Mathis DT; Eggeling L; Eckl L; Merkely G; Wafaisade A; Schuettler KF; Guenther D; Kittl C; Res Komitee Arbeitsgemeinschaft Arthroskopie AGA

Abstract

Stress X-ray images are an established method for the objective assessment of ligamentous knee joint instability. They enable a reproducible and objective quantification of joint instability under standardized conditions in cases of cruciate ligament injuries as well as lesions of the medial and lateral collateral ligaments. The assessment of patellofemoral instability is more neglected and only exists experimentally. Depending on the suspected instability, different loading directions and knee flexion angles are considered: anterior or posterior stress for cruciate ligament injuries (typically at 90 degrees flexion) and valgus or varus stress for collateral ligament injuries (at 0 degrees and 20 degrees flexion). Loading is applied either manually or using mechanical devices such as the Telos system with defined force application. The resulting joint space changes (medial or lateral) or translational differences of the tibia compared to the femur are assessed radiographically and compared with the contralateral side. Clinically relevant instability can thus be objectively identified. A standardized technique and precise patient positioning are essential for diagnostic accuracy. Stress radiography therefore plays a key role in the differential diagnostics of complex ligament injuries and supports both treatment planning and decision making regarding surgical or conservative treatment and serves as quality control in postoperative follow-up.