The biomechanics of step descent under different treatment modalities used in patellofemoral pain

Abstract

Background Most previous work on the use of knee bracing and taping has focussed on sagittal plane movement. However, most bracing and taping techniques aim to modify patellar movement in the coronal and transverse planes. Objective This study investigated the effect of patellar bracing and taping on the three-dimensional mechanics of the knee during a controlled eccentric step down task. Method Twelve healthy subjects were asked to conduct a slow step down exercise. The step down was conducted under three randomised conditions: (a) no intervention, (b) neutral patella taping and (c) patellofemoral bracing. A step was constructed to accommodate an AMTI force platform and to produce a step height of 20 cm. Kinematic data were collected using a six camera ProReflex motion analysis system. Reflective markers were placed on the foot, shank and thigh using the Calibrated Anatomical Systems Technique (CAST). Results The patellofemoral brace and taping led to a significant reduction in the maximum coronal and range of torsional knee angles by 5° and 2°, respectively ( p = 0.030, 0.006). The range of coronal and transverse plane knee moments was also significantly reduced by 0.15 Nm/kg and 0.03 Nm/kg ( p = 0.020, 0.0019). The brace was shown to be more effective in the coronal and transverse planes in comparison to taping or no intervention. Conclusion Bracing and taping appear to offer coronal plane and torsional control of the knee during eccentric step descent. Coronal and transverse plane mechanics should not be overlooked when studying patellofemoral pain.