Increasing the posterior tibial slope lowers in situ forces in the native ACL primarily at deep flexion angles

• High tibial osteotomy is becoming increasingly popular but can be associated with unintentional posterior tibial slope (PTS) increase and subsequent anterior cruciate ligament (ACL) degeneration. This study quantified the effect of increasing PTS on knee kinematics and in situ forces in the native ACL. A robotic testing system was used to apply external loads from full extension to 90 degrees flexion to seven human cadaveric knees: (1) 200 N axial compressive load, (2) 5 Nm internal tibial + 10 Nm valgus torque, and (3) 5 Nm external tibial + 10 Nm varus torque. Kinematics and in situ forces in the ACL were acquired for the native and increased PTS state. Increasing PTS resulted in increased anterior tibial translation at 30 degrees (1.8 mm), 60 degrees (1.7 mm), and 90 degrees (0.9 mm) flexion and reduced in situ force in the ACL at 30 degrees (57.6%), 60 degrees (69.8%), and 90 degrees (75.0%) flexion in response to 200 N axial compressive load. In response to 5 Nm internal tibial + 10 Nm valgus torque, there was significantly less (39.0%) in situ force in the ACL at 90 degrees flexion in the increased compared with the native PTS state. Significantly less in situ force in the ACL at 60 degrees (62.8%) and 90 degrees (67.0%) flexion was observed in the increased compared with the native PTS state in response to 5 Nm external tibial + 10 Nm varus torque. Increasing PTS affects knee kinematics and results in a reduction of in situ forces in the native ACL during compressive and rotatory loads at flexion angles exceeding 30 degrees. In a controlled laboratory setting PTS increase unloads the ACL, affecting its natural function.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Ortopedi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Orthopaedics (hsv//eng)

Nyckelord

ACL

HTO

kinematics

osteotomy

slope

anterior cruciate ligament

knee stability

osteotomy

reconstruction

revision

outcomes

system

tendon

sensor

Orthopedics

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