Iliotibial band tension reduces patellar lateral stability

Abstract

This study investigated the effect of loading the iliotibial band (ITB) on the stability of the patellofemoral joint. We measured the restraining force required to displace the patella 10 mm medially and laterally (defined as medial and lateral stability, respectively) in 14 fresh-frozen knees from 0 to 90° knee flexion. The testing rig allowed the patella to rotate and translate freely during this displacement. The quadriceps was separated into five components and loaded with 175 N total tension. Testing was performed at 0 to 90 N ITB tension. With no ITB tension, the lateral restraining force ranged from 82 to 101 N across 0 to 90° flexion. Increasing ITB tension caused progressive reduction of the lateral restraining force. The maximum reduction was 25% at 60° flexion and 90 N ITB tension. Medial restraining force increased progressively with increasing knee flexion and increasing ITB loads; it ranged from 74 N at 0° knee flexion and 0 N ITB tension to 211 N at 90° knee flexion and 90 N ITB tension. The maximum effect was an increase of medial restraining force of 50% at 90° flexion and 90 N ITB tension. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.